You can easily build your own ingame GUI or draw custom shapes / icons / pictures through LUA. Each rendered frame the “Gameloop.Draw” - LUA-Event is called. You need to register your LUA function for this event and then you can build your GUI in there. Example: To get you started, let's draw a simple window with a slider, create a new .lua file, add it to your addon's module.def and put the following code into that new lua file:

-- Draws a Window with a Slider:
my_gui = {}
my_gui.open = true
my_gui.visible = true
my_gui.hue = 125
 
function my_gui.Draw( event, ticks ) 	
 
	if ( my_gui.open ) then 
 
           GUI:SetNextWindowSize(250,400,GUI.SetCond_FirstUseEver) -- set the next window size, only on first ever, GUI.SetCond_FirstUseEver is one of many possible enums.
 
           --GUI:Begin takes in two arguments, the name of the window and the current "is open" bool. It returns "is visible/is not collapsed" and the "is open" bool again.
           --If the user would close our Window, "is open" would return "false", else it will keep returning "true" as long as the window is open.
	   my_gui.visible, my_gui.open = GUI:Begin("My Fancy GUI", my_gui.open)
 
           if ( my_gui.visible ) then -- visible is true/false depending if the window is collapsed or not, we don't have to render anything in it when it is collapsed
                -- Again the typical syntax, passing the current value "hue" to the function as argument and receiving back the (un-)changed value. 
	   	my_gui.hue = GUI:SliderInt("Master HUE",my_gui.hue,0,255)
	        d(my_gui.hue)  -- spam print out the current value
	   end
	   GUI:End()  -- THIS IS IMPORTANT! For EVERY BEGIN() you NEED to ALWAYS call END(), it does not matter if the window is visible/open or not! Same goes with BeginChild() & EndChild() and others !
        end	
end
RegisterEventHandler("Gameloop.Draw", my_gui.Draw)

• To get an overview what is possible with the GUI, open the ingame console (CTRL + C) and execute this command: ml_gui.showtestwindow = true
  
• If you find something in that Testwindow but you are not sure how to code the same in LUA, have a look in the c++ source of it: https://github.com/ocornut/imgui/blob/master/imgui_demo.cpp, the used function names and syntax are 99% the same, just the arguments might be slightly different due to LUA not supporting references.
  

• Underlined function arguments in the following API documentation are optional. Example: GUI:Begin(string name, bool open, windowflags flags)

• Most UI Element “names” or “labels” are at the same time their internal identifier which has to be unique. You can use the following to make that happen:

Example: Same name in UI, different internal identifier:
GUI:Button("Banana")
GUI:Button("Banana##1")
Example: Different name in UI, same internal identifier: 
GUI:Button("Banana###123hohoho") 
GUI:Button("Pineapple###123hohoho")

• GUI:ShowTestWindow(bool isopen)
  • Returns: bool isopen
  • Test window, demonstrates GUI features

• GUI:ShowMetricsWindow(bool isopen)
  • Returns: bool isopen
  • Metrics window for debuggings

• GUI:Begin(string name, bool open, windowflags flags)
  • Returns bool visible, bool open
  • visible means “not collapsed”, so can opt out early when window is collapsed. For WindowFlags, check the Enums & Flags further below on this page.

• GUI:End()
  • For every GUI:Begin(..) call, you need to call GUI:End(), independent if the the window is opened/shown or not.

• GUI:BeginChild(string name, int sizeX, int sizeY, bool border, windowflags flags
  • Begin a scrolling region. size==0.0f: use remaining window size, size<0.0f: use remaining window size minus abs(size). size>0.0f: fixed size. each axis can use a different mode, e.g. sizeX=0 & sizeY=400.

• GUI:EndChild()
  • For every GUI:BeginChild(..) call, you need to call GUI:EndChild().

• GUI:IsWindowAppearing()
  • Returns: bool

• GUI:IsWindowCollapsed()
  • Returns: bool

• GUI:IsWindowFocused(FocusedFlags flags)
  • Returns: bool
  • is current window focused? or its root/child, depending on flags. see flags for options.

• GUI:IsWindowHovered(HoveredFlags flags)
  • Returns: bool
  • is current window hovered (and typically: not blocked by a popup/modal)? see flags for options.

• GUI:GetWindowPos()
  • Returns: number x, number y
  • get current window position in screen space

• GUI:GetWindowSize()
  • Returns: number x, number y
  • get current window size

• GUI:GetWindowWidth()
  • Returns: number width

• GUI:GetWindowHeight()
  • Returns: number height

• GUI:GetContentRegionMax()
  • Returns: number x, number y
  • current content boundaries (typically window boundaries including scrolling, or current column boundaries), in windows coordinates

• GUI:GetContentRegionAvail()
  • Returns: number x, number y
  • == GetContentRegionMax() - GetCursorPos()

• GUI:GetContentRegionAvailWidth()
  • Returns: number width

• GUI:GetWindowContentRegionMin()
  • Returns: number x, number y
  • content boundaries min (roughly (0,0)-Scroll), in window coordinates

• GUI:GetWindowContentRegionMax()
  • Returns: number x, number y
  • content boundaries max (roughly (0,0)+Size-Scroll) where Size can be override with SetNextWindowContentSize(), in window coordinates

• GUI:GetWindowContentRegionWidth()
  • Returns: number witdth

• GUI:SetNextWindowPos( number X, number Y, SetCondflags flags)
  • set next window position. call before Begin()

• GUI:SetNextWindowSize( number X, number Y, SetCondflags flags)
  • set next window size. set axis to 0.0f to force an auto-fit on this axis. call before Begin()

• GUI:SetNextWindowContentSize( number X, number Y)
  • set next window content size (enforce the range of scrollbars). set axis to 0.0f to leave it automatic. call before Begin()

• GUI:SetNextWindowCollapsed( bool collapsed, SetCondflags flags)
  • set next window collapsed state. call before Begin()

• GUI:SetNextWindowFocus()
  • set next window to be focused / front-most. call before Begin()

• GUI:SetWindowPos( number X, number Y, SetCondflags flags)
  • set current window position - call within Begin()/End().

• GUI:SetWindowPos( string name, number X, number Y, SetCondflags flags)
  • set current window position - call within Begin()/End(). may incur tearing

• GUI:SetWindowSize( number X, number Y, SetCondflags flags)
  • set current window size. set X,Y to 0 to force an auto-fit.

• GUI:SetWindowSize( string name, number X, number Y, SetCondflags flags)
  • set named window size. set X,Y to 0 to force an auto-fit on this axis.

• GUI:SetWindowCollapsed( bool collapsed, SetCondflags flags)
  • set current window collapsed state

• GUI:SetWindowCollapsed( string name, bool collapsed, SetCondflags flags)
  • set named window collapsed state

• GUI:SetWindowFocus( string name)
  • set current/named window to be focused / front-most

• GUI:GetScrollX()
  • Returns: get scrolling amount [0..GetScrollMaxX()]

• GUI:GetScrollY()
  • Returns: get scrolling amount [0..GetScrollMaxY()]

• GUI:GetScrollMaxX()
  • Returns: get maximum scrolling amount ~~ ContentSize.X - WindowSize.X

• GUI:GetScrollMaxY()
  • Returns: get maximum scrolling amount ~~ ContentSize.Y - WindowSize.Y

• GUI:SetScrollX( number scrollX)
  • set scrolling amount [0..GetScrollMaxX()]

• GUI:SetScrollY( number scrollX)
  • set scrolling amount [0..GetScrollMaxY()]

• GUI:SetScrollHere( number center_y_ratio)
  • adjust scrolling amount to make current cursor position visible. center_y_ratio=0.0: top, 0.5: center, 1.0: bottom.

• GUI:SetScrollFromPosY( number pos_y, number center_y_ratio)
  • adjust scrolling amount to make given position valid. use GetCursorPos() or GetCursorStartPos()+offset to get valid positions.

• GUI:SetKeyboardFocusHere(number offset)
  • focus keyboard on the next widget. Use positive 'offset' to access sub components of a multiple component widget

• GUI:PushStyleColor(PushStyleColor flags, number R, number G, number B, number A)
  • sets the color for the following elements

• GUI:PopStyleColor( number count )
  • removes the last pushed color style(s)

• GUI:PushStyleVar(PushStyleVar flags, number val, number val2)
  • sets the style for the following elements

• GUI:PopStyleVar( number count )
  • removes the last pushed style var(s)

• GUI:GetColorU32( number r, number g, number b, number a )
  • Returns: number color

• GUI:PushItemWidth( number item_width )
  • width of items for the common item+label case, pixels. 0.0f = default to ~2/3 of windows width, >0.0f: width in pixels, <0.0f align xx pixels to the right of window (so -1.0f always align width to the right side))

• GUI:PopItemWidth( )
  • removes the last pushed item width

• GUI:CalcItemWidth( )
  • width of item given pushed settings and current cursor position

• GUI:PushTextWrapPos( number wrap_pos_x )
  • word-wrapping for Text*() commands. < 0.0f: no wrapping; 0.0f: wrap to end of window (or column); > 0.0f: wrap at 'wrap_pos_x' position in window local space

• GUI:PopTextWrapPos( )
  • removes the last pushed wrap pos

• GUI:PushAllowKeyboardFocus( bool val )
  • allow focusing using TAB/Shift-TAB, enabled by default but you can disable it for certain widgets

• GUI:PopAllowKeyboardFocus( )
  • removes the last pushed keyboard focus setting

• GUI:PushButtonRepeat( bool repeat)
  • in 'repeat' mode, Button functions return repeated true in a typematic manner.

• GUI:PopButtonRepeat( )
  • removes the last pushed button repeat setting

• GUI:GetWindowFontSize()
  • Returns: number size
  • size (also height in pixels) of current font with current scale applied

• GUI:GetWindowFontSize( number scale)
  • per-window font scale. Adjust IO.FontGlobalScale if you want to scale all windows

• GUI:GetGlobalFontSize()
  • Returns: number size of global font scale

• GUI:SetGlobalFontSize( number scale)
  • sets global font scale

• GUI:AlignTextToFramePadding( )
  • If a line does not start with text but with an Icon or other GUI Element, call this before drawing the text to align the height correctly.

• GUI:Separator( )
  • horizontal line

• GUI:SameLine( number local_pos_x, number spacing_w )
  • call between widgets or groups to layout them horizontally

• GUI:NewLine()
  • undo a SameLine()

• GUI:Spacing( )
  • add spacing

• GUI:Dummy( number sizeX, number sizeY )
  • add a dummy item of given size

• GUI:Indent( )
  • move content position toward the right by style.IndentSpacing pixels

• GUI:Unindent( )
  • move content position back to the left (cancel Indent)

• GUI:BeginGroup( )
  • lock horizontal starting position. once closing a group it is seen as a single item (so you can use GUI:IsItemHovered() on a group, GUI:SameLine() between groups, etc.

• GUI:EndGroup( )
  • Needs to be called for each GUI:BeginGroup()

• GUI:Columns( number count, string name, bool border )
  • setup number of columns. use an identifier to distinguish multiple column sets. close with Columns(1).

• GUI:NextColumn( )
  • next column

• GUI:GetColumnIndex( )
  • Returns: number current column index

• GUI:GetColumnOffset( number column_index )
  • Returns: number get position of column line (in pixels, from the left side of the contents region). pass -1 to use current column, otherwise 0..GUI:GetcolumnsCount() inclusive. column 0 is usually 0.0f and not resizable unless you call this

• GUI:SetColumnOffset( number column_index, number offset_x )
  • set position of column line (in pixels, from the left side of the contents region). pass -1 to use current column

• GUI:GetColumnWidth( number column_index )
  • Returns: number column width (== GUI:GetColumnOffset(GetColumnIndex()+1) - GUI:GetColumnOffset(GetColumnOffset())

• GUI:SetColumnWidth( number column_index, number width )
  • set column width (in pixels). pass -1 to use current column

• GUI:GetColumnsCount( )
  • Returns: number number of columns (what was passed to Columns())

• GUI:GetTextLineHeight( )
  • Returns: number FontSize

• GUI:GetTextLineHeightWithSpacing( )
  • Returns: number FontSize + style.ItemSpacing.y (distance in pixels between 2 consecutive lines of text)

• GUI:GetFrameHeight( )
  • Returns: number FontSize + style.FramePadding.y * 2

• GUI:GetFrameHeightWithSpacing( )
  • Returns: number FontSize + style.FramePadding.y * 2 + style.ItemSpacing.y (distance in pixels between 2 consecutive lines of framed widgets)

• GUI:GetCursorPos( )
  • Returns: number x, number y
  • cursor position is relative to window position

• GUI:GetCursorPosX( )
  • Returns: number x

• GUI:GetCursorPosY( )
  • Returns: number y

• GUI:SetCursorPos( number x, number y )
  • sets cursor position is relative to window position

• GUI:SetCursorPosX( number x )
  • sets cursor position x

• GUI:SetCursorPosY( number y )
  • sets cursor position y

• GUI:GetCursorStartPos( )
  • Returns: number x, number y
  • initial cursor position

• GUI:GetCursorScreenPos( )
  • Returns: number x, number y
  • cursor position in absolute screen coordinates [0..io.DisplaySize]

• GUI:SetCursorScreenPos( number x, number y )
  • cursor position in absolute screen coordinates [0..io.DisplaySize]

If you are creating multiple GUI Elements you want to push a unique identifier so ImGui can differentiate them. You can also use “##extra” within your widget name to distinguish them from each others.

• GUI:PushID( string id)
  • push identifier into the ID stack.

• GUI:PopID( )
  • pops the last pushed identifier from the ID stack.

• GUI:GetID( string id)
  • calculate unique ID

• GUI:Text( string text)
  • creates a text element

• GUI:TextColored( number R, number G, number B, number A, string text)
  • creates a colored text element, number range is 0.0 - 1.0

• GUI:TextDisabled( string text)
  • creates a disabled text element

• GUI:TextWrapped( string text)
  • creates a text element which wraps

• GUI:TextUnformatted( string text)
  • creates an unformatted text element

• GUI:LabelText( string label, string text)
  • display text+label aligned the same way as value+label widgets

• GUI:Bullet( )
  • creates a bullet element

• GUI:BulletText( string text)
  • creates a bullet text element

• GUI:Button( string label, number sizeX, number sizeY)
  • creates a buttom element

• GUI:SmallButton( string label)
  • creates a smaller button element

• GUI:ArrowButton( string label, Direction direction )
  • creates an arrowbutton

• GUI:InvisibleButton( string label, number sizeX, number sizeY)
  • creates an invisible button element

• GUI:ColorButton( string id, number R, number G, number B, number A, ColorEditMode flags, number sizeX, number sizeY)
  • Returns: bool pressed

• GUI:FreeButton( string label, number posX, number posY, number sizeX, number sizeY)
  • creates a freely placable buttom element

• GUI:FreeImageButton( /string internalid, string filepath, number posX, number posY, number sizeX, number sizeY)
  • creates a freely placable image buttom element

• GUI:ImageButton(string internalid, string filepath, number sizeX, number sizeY, number UV0_x, number UV0_y, number UV1_x, number UV1_y, number framepadding,number bg_col_R, number bg_col_G, number bg_col_B, number bg_col_A, number tint_col_R, number tint_col_G, number tint_col_B, number tint_col_A )
  • creates an image button, scary eh ;) ? Simple usage: GUI:ImageButton( string internalid, string filepath, number sizeX, number sizeY).
  • < 0 frame_padding uses default frame padding settings. 0 for no padding

• GUI:Image(string filepath, number sizeX, number sizeY, number UV0_x, number UV0_y, number UV1_x, number UV1_y, number bg_col_R, number bg_col_G, number bg_col_B, number bg_col_A, number tint_col_R, number tint_col_G, number tint_col_B, number tint_col_A )
  • Simple Usage: GUI:Image(string filepath, number sizeX, number sizeY)

• GUI:Checkbox( string label, bool checked)
  • Returns: bool checked, bool pressed

• GUI:CheckboxFlags( string label, number flags, number flags_value)
  • Returns: number flags, bool pressed

• GUI:RadioButton( string label, bool active)
  • Returns: bool active

• GUI:RadioButton( string label, bool active, number val)
  • Returns: number val, bool pressed

• GUI:BeginCombo( string label, string preview_value, ComboFlag)
  • Returns: bool val, BeginCombo()/EndCombo() api allows you to manage your contents and selection state however you want it. Refer to https://github.com/ocornut/imgui/blob/master/imgui_demo.cpp to see how it has to be used.

• GUI:EndCombo()
  • only call EndCombo() if BeginCombo() returns true!

• GUI:Combo( string label, number current_item_listindex, table itemlist, number height_in_items)
  • Returns: number current_item_listindex, bool changed

• GUI:ProgressBar( number fraction, number SizeX, number SizeY, string overlay )
  • Guess what it draws ;)

(Tip: ctrl+click on a drag box to input text)

• GUI:DragFloat( string label, number val, number v_speed, number v_min, number v_max, string display_format, number power)
  • Returns: number val, bool changed
  • display_format example “%.3f”, *If v_min >= v_max we have no bound

• GUI:DragFloatRange2( string label, number v_current_min, number v_current_max, number v_speed, number v_min, number v_max, string display_format, string display_format_max, number power)
  • Returns: number val_min, number val_max, bool changed
  • display_format example “%.3f”, *If v_min >= v_max we have no bound

• GUI:DragInt( string label, number val, number v_speed, number v_min, number v_max, string display_format)
  • Returns: number val, bool changed
  • display_format example “%.3f”, *If v_min >= v_max we have no bound

• GUI:DragIntRange2( string label, number v_current_min, number v_current_max, number v_speed, number v_min, number v_max, string display_format, string display_format_max)
  • Returns: number val_min, number val_max, bool changed
  • display_format example “%.3f”, *If v_min >= v_max we have no bound

• GUI:InputText( string label, string text, InputTextFlags flags)
  • Returns: string text, bool changed

• GUI:InputTextMultiline( string label, string text, number sizeX, number sizeY , InputTextFlags flags)
  • Returns: string text, bool changed

• GUI:InputFloat( string label, number val, number step, number step_fast, number decimal_precision, InputTextFlags flags)
  • Returns: number val, bool changed

• GUI:InputFloat2( string label, number val, number val2, number decimal_precision, InputTextFlags flags)
  • Returns: number val, number val2, bool changed
  • Draws 2 Input fields behind each other in the same line

• GUI:InputFloat3( string label, number val, number val2, number val3, number decimal_precision, InputTextFlags flags)
  • Returns: number val, number val2, number val3, bool changed
  • Draws 3 Input fields behind each other in the same line

• GUI:InputFloat4( string label, number val, number val2, number val3, number val4, number decimal_precision, InputTextFlags flags)
  • Returns: number val, number val2, number val3, number val4, bool changed
  • Draws 4 Input fields behind each other in the same line

• GUI:InputInt( string label, number val, number step, number step_fast, InputTextFlags flags)
  • Returns: number val, bool changed

• GUI:InputInt2( string label, number val, number val2, InputTextFlags flags)
  • Returns: number val, number val2, bool changed
  • Draws 2 Input fields behind each other in the same line

• GUI:InputInt3( string label, number val, number val2, number val3, InputTextFlags flags)
  • Returns: number val, number val2, number val3, bool changed
  • Draws 3 Input fields behind each other in the same line

• GUI:InputInt4( string label, number val, number val2, number val3, number val4, InputTextFlags flags)
  • Returns: number val, number val2, number val3, number val4, bool changed
  • Draws 4 Input fields behind each other in the same line

• GUI:SliderFloat( string label, number val, number v_min, number v_max, string display_format, number power)
  • Returns: number val, bool changed

• GUI:SliderFloat2( string label, number val, number val2, number v_min, number v_max, string display_format, number power)
  • Returns: number val, number val2, bool changed
  • Draws 2 Input fields behind each other in the same line

• GUI:SliderFloat3( string label, number val, number val2, number val3, number v_min, number v_max, string display_format, number power)
  • Returns: number val, number val2, number val3, bool changed
  • Draws 3 Input fields behind each other in the same line

• GUI:SliderFloat4( string label, number val, number val2, number val3, number val4, number v_min, number v_max, string display_format, number power)
  • Returns: number val, number val2, number val3, number val4, bool changed
  • Draws 4 Input fields behind each other in the same line

• GUI:SliderAngle( string label, number v_rad, number v_degrees_min, number v_degrees_max)
  • Returns: number val, bool changed

• GUI:SliderInt( string label, number val, number v_min, number v_max, string display_format)
  • Returns: number val, bool changed

• GUI:SliderInt2( string label, number val, number val2, number v_min, number v_max, string display_format)
  • Returns: number val, number val2, bool changed

• GUI:SliderInt3( string label, number val, number val2, number val3, number v_min, number v_max, string display_format)
  • Returns: number val, number val2, number val3, bool changed

• GUI:SliderInt4( string label, number val, number val2, number val3, number val4, number v_min, number v_max, string display_format)
  • Returns: number val, number val2, number val3, number val4, bool changed

• GUI:VSliderFloat( string label, number sizeX, number sizeY, number val, number v_min, number v_max, string display_format, number power)
  • Returns: number val, bool changed

• GUI:VSliderInt( string label, number sizeX, number sizeY, number val, number v_min, number v_max, string display_format)
  • Returns: number val, bool changed

• GUI:ColorEdit3( string label, number R, number G, number B, ColorEditMode flags)
  • Returns: number R, number G, number B, bool changed

• GUI:ColorEdit4( string label, number R, number G, number B, number A, ColorEditMode flags)
  • Returns: number R, number G, number B, number A, bool changed

• GUI:ColorPicker3( string label, number R, number G, number B, ColorEditMode flags)
  • Returns: number R, number G, number B, bool changed

• GUI:ColorPicker4( string label, number R, number G, number B, number A, ColorEditMode flags)
  • Returns: number R, number G, number B, number A, bool changed

• GUI:ColorEditMode( ColorEditMode mode)
  • sets ColorEditMode

• GUI:TreeNode( string label)
  • Returns: bool changed , if returning 'true' the node is open and the user is responsible for calling TreePop()

• GUI:TreeNode( string label, string args)
  • Returns: bool changed , if returning 'true' the node is open and the user is responsible for calling TreePop()

• GUI:TreeNode( string label, TreeNodeFlag flags, string args)
  • Returns: bool changed , if returning 'true' the node is open and the user is responsible for calling TreePop()

• GUI:TreePush( string id)
  • already called by TreeNode(), but you can call Push/Pop yourself for layouting purpose

• GUI:TreePop( )
  • needs to be callled at the end of TreePush()

• GUI:SetNextTreeNodeOpened( bool opened, SetCond flags)
  • set next tree node to be opened.

• GUI:CollapsingHeader( string label, TreeNodeFlag flags)
  • Returns: bool collapsed, if returning 'true' the header is open. doesn't indent nor push on ID stack. user doesn't have to call TreePop().

• GUI:CollapsingHeader( string label, bool p_open, TreeNodeFlag flag)
  • Returns: bool collapsed, when 'p_open' isn't NULL, display an additional small close button on upper right of the header

• GUI:Selectable( string label, bool selected, SelectableFlag flags, number sizeX, number sizeY )
  • Returns: bool changed
  • size.x==0.0: use remaining width, size.x>0.0: specify width. size.y==0.0: use label height, size.y>0.0: specify height

• GUI:ListBox( string label, number current_listitem_index, table itemlist, number height_in_items )
  • Returns: number current_item_index, bool changed

• GUI:ListBoxHeader( string label, number items_count, number height_in_items )
  • Returns: bool
  • use if you want to reimplement ListBox() will custom data or interactions. make sure to call ListBoxFooter() afterwards.

• GUI:ListBoxFooter( )
  • terminate the scrolling region

• GUI:SetTooltip( string label )
  • set tooltip under mouse-cursor, typically use with GUI:IsHovered(). last call wins
• GUI:BeginTooltip( )
  • use to create full-featured tooltip windows that aren't just text
• GUI:EndTooltip( )
  • use to create full-featured tooltip windows that aren't just text

• GUI:BeginMainMenuBar( )
  • Returns: bool opened
  • create and append to a full screen menu-bar. only call EndMainMenuBar() if this returns true!
• GUI:EndMainMenuBar( )
  • End Menubar drawing
• GUI:BeginMenuBar( )
  • Returns: bool opened
  • append to menu-bar of current window (requires ImGuiWindowFlags_MenuBar flag set). only call EndMenuBar() if this returns true!
• GUI:EndMenuBar( )
  • End Menubar drawing
• GUI:BeginMenu( string label, bool enabled )
  • Returns: bool opened
  • create a sub-menu entry. only call EndMenu() if this returns true!
• GUI:EndMenu( )
  • End Menubar drawing
• GUI:MenuItem( string label, string shortcut, bool selected, bool enabled)
  • Returns: bool activated, bool selected
  • Shortcuts are currently only visual, aka not working, you need to add that yourself

• GUI:OpenPopup( string id)
  • mark popup as open. popups are closed when user click outside, or activate a pressable item, or CloseCurrentPopup() is called within a BeginPopup()/EndPopup() block. popup identifiers are relative to the current ID-stack (so OpenPopup and BeginPopup needs to be at the same level).

• GUI:BeginPopup( string id, WindowFlags flags)
  • Returns: bool open
  • return true if popup if opened and start outputting to it. only call EndPopup() if BeginPopup() returned true!

• GUI:BeginPopupModal( string name, bool opened, WindowFlags flags)
  • Returns bool visible, bool open
  • modal dialog (can't close them by clicking outside)

• GUI:BeginPopupContextItem( string id, number mouse_button)
  • Returns bool open
  • helper to open and begin popup when clicked on last item

• GUI:BeginPopupContextWindow( string id, number mouse_button, bool also_over_items)
  • Returns bool open
  • helper to open and begin popup when clicked on current window

• GUI:BeginPopupContextVoid( string id, number mouse_button)
  • Returns bool open
  • helper to open and begin popup when clicked in void (no window)

• GUI:EndPopup( )
  • needs to be called on opened popups

• GUI:IsPopupOpen( string id)
  • Returns bool open

• GUI:CloseCurrentPopup( )
  • close the popup we have begin-ed into. clicking on a MenuItem or Selectable automatically close the current popup.

• GUI:IsItemHovered( HoveredFlags flags )
  • Results: bool
  • is the last item hovered? (and usable, aka not blocked by a popup, etc.).

• GUI:IsItemActive( )
  • Results: bool
  • is the last item active? (e.g. button being held, text field being edited- items that don't interact will always return false)

• GUI:IsItemFocused( )
  • Results: bool
  • is the last item focused for keyboard/gamepad navigation?

• GUI:IsItemClicked( int mousebutton == 0)
  • Results: bool
  • was the last item clicked? (e.g. button/node just clicked on)

• GUI:IsItemVisible( )
  • Results: bool
  • was the last item visible? (aka not out of sight due to clipping/scrolling.)

• GUI:IsAnyItemHovered( )
  • Results: bool

• GUI:IsAnyItemActive( )
  • Results: bool

• GUI:IsAnyItemFocused( )
  • Results: bool
  • is the any item focused for keyboard/gamepad navigation?

• GUI:GetItemRectMin( )
  • Results: number x, number y
  • get bounding rect of last item in screen space

• GUI:GetItemRectMax( )
  • Results: number x, number y
  • get bounding rect of last item in screen space

• GUI:GetItemRectSize( )
  • Results: number x, number y

• GUI:SetItemAllowOverlap( )
  • Allow last item to be overlapped by a subsequent item. sometimes useful with invisible buttons, selectables, etc. to catch unused area.

• GUI:IsRectVisible( number x, number y)
  • Results: bool
  • test if rectangle of given size starting from cursor pos is visible (not clipped). to perform coarse clipping on user's side

• GUI:GetTime( )
  • Results: number

• GUI:GetFrameCount( )
  • Results: number

• GUI:CalcTextSize( string text)
  • Results: number sizex, number sizey

• GUI:CalcListClipping( number items_count, number items_height, number out_items_display_start, number out_items_display_end)
  • Results: number out1, number out2
  • calculate coarse clipping for large list of evenly sized items. Prefer using the ImGuiListClipper higher-level helper if you can.

• GUI:BeginChildFrame( number guiID, number sizex, number sizey, WindowFlags flags)
  • Results: bool
  • helper to create a child window / scrolling region that looks like a normal widget frame

• GUI:EndChildFrame( )
  • needs to be called at the end of BeginChildFrame.

• GUI:ColorConvertU32ToFloat4( number U32val)
  • Returns: number val1,number val2,number val3,number val4

• GUI:ColorConvertFloat4ToU32( number val1,number val2,number val3,number val4 )
  • Returns: number U32val

• GUI:ColorConvertRGBtoHSV( number r, number g, number b)
  • Returns: number h, number s, number v

• GUI:ColorConvertHSVtoRGB( number h, number s, number v)
  • Returns: number r, number g, number b

• GUI:GetScreenSize()
  • Returns: number x, number y

• GUI:IsKeyDown( number virtualkey)
  • Returns: bool
  • https://msdn.microsoft.com/en-us/library/windows/desktop/dd375731%28v=vs.85%29.aspx for all values, convert the hex to decimal values

• GUI:IsKeyPressed( number virtualkey, bool repeat)
  • Returns: bool
  • https://msdn.microsoft.com/en-us/library/windows/desktop/dd375731%28v=vs.85%29.aspx for all values, convert the hex to decimal values

• GUI:IsKeyReleased( number virtualkey)
  • Returns: bool
  • https://msdn.microsoft.com/en-us/library/windows/desktop/dd375731%28v=vs.85%29.aspx to for values, convert the hex to decimal values

• GUI:IsMouseDown( number button)
  • Returns: bool

• GUI:IsMouseClicked( number button, bool repeat)
  • Returns: bool

• GUI:IsMouseDoubleClicked( number button)
  • Returns: bool

• GUI:IsMouseReleased( number button)
  • Returns: bool

• GUI:IsMouseHoveringWindow( number button)
  • Returns: bool
  • is mouse hovering current window (“window” in API names always refer to current window). disregarding of any consideration of being blocked by a popup. (unlike IsWindowHovered() this will return true even if the window is blocked because of a popup)

• GUI:IsMouseHoveringAnyWindow( number button)
  • Returns: bool

• GUI:IsMouseHoveringAnyWindow( number pos_minX, number pos_minY, number pos_maxX, number pos_maxY, bool clip)
  • Returns: bool
  • is mouse hovering given bounding rect (in screen space). clipped by current clipping settings. disregarding of consideration of focus/window ordering/blocked by a popup.

• GUI:IsMouseDragging( number button, number lock_threshold)
  • Returns: bool

• GUI:GetMousePos( )
  • Returns: number x, number y

• GUI:GetMousePosOnOpeningCurrentPopup( )
  • Returns: number x, number y
  • retrieve backup of mouse positioning at the time of opening popup we have BeginPopup() into

• GUI:GetMouseDragDelta( number button, number lock_threshold)
  • Returns: number x, number y
  • dragging amount since clicking.

• GUI:ResetMouseDragDelta( number button)
  • Banana ;)

• GUI:GetClipboardText()
  • get text data from the clipboard

• GUI:SetClipboardText( string input)
  • set text data to the clipboard

Usage: GUI:AddCircleFilled( 300, 300, 475,GUI:ColorConvertFloat4ToU32(0.9,0.1,0.12,0.5)) IMPORTANT: Use GUI:ColorConvertFloat4ToU32() to calculatethe required numbercolor argument!!

• GUI:AddLine( number X1, number Y1, number X2, number Y2, number color, number thickness = 1.0,)

• GUI:AddRect( number X1, number Y1, number X2, number Y2, number color, number rounding= 0.0, number rounding_corners = 0.0)

• GUI:AddRectFilled( number X1, number Y1, number X2, number Y2, number color, number rounding= 0.0, number rounding_corners = 0.0)

• GUI:AddQuadFilled( number X1, number Y1, number X2, number Y2, number X3, number Y3, number X4, number Y4, number color)

• GUI:AddTriangleFilled( number X1, number Y1, number X2, number Y2, number X3, number Y3, number color)

• GUI:AddCircle( number X1, number Y1, number radius, number color, number num_segments= 12)

• GUI:AddCircleFilled( number X1, number Y1, number radius, number color, number num_segments= 12)

• GUI:AddText( number X1, number Y1, number color, string text)

• GUI:AddImage( string texturepath, number X1, number Y1, number X2, number Y2)

• RenderManager:WorldToScreen(table worldpos)
  • Returns: table screenpos
  • Converts a worldposition x,y,z to a screenposition x,y , IF that point is currently visible on the screen

These are registered values in the GUI metatable. Usage: d(GUI.WindowFlags_NoMove) will print “2” into the console.

• GUI.WindowFlags_NoTitleBar
• GUI.WindowFlags_NoResize
• GUI.WindowFlags_NoMove
• GUI.WindowFlags_NoScrollbar
• GUI.WindowFlags_NoScrollWithMouse
• GUI.WindowFlags_NoCollapse
• GUI.WindowFlags_AlwaysAutoResize
• GUI.WindowFlags_NoSavedSettings
• GUI.WindowFlags_NoInputs
• GUI.WindowFlags_MenuBar
• GUI.WindowFlags_HorizontalScrollbar
• GUI.WindowFlags_NoFocusOnAppearing
• GUI.WindowFlags_NoBringToFrontOnFocus
• GUI.WindowFlags_ForceVerticalScrollbar
• GUI.WindowFlags_ForceHorizontalScrollbar
• GUI.WindowFlags_AlwaysUseWindowPadding

• GUI.InputTextFlags_CharsDecimal
• GUI.InputTextFlags_CharsHexadecimal
• GUI.InputTextFlags_CharsUppercase
• GUI.InputTextFlags_CharsNoBlank
• GUI.InputTextFlags_AutoSelectAll
• GUI.InputTextFlags_EnterReturnsTrue
• GUI.InputTextFlags_CallbackCompletion
• GUI.InputTextFlags_CallbackHistory
• GUI.InputTextFlags_CallbackAlways
• GUI.InputTextFlags_CallbackCharFilter
• GUI.InputTextFlags_AllowTabInput
• GUI.InputTextFlags_CtrlEnterForNewLine
• GUI.InputTextFlags_NoHorizontalScroll
• GUI.InputTextFlags_AlwaysInsertMode
• GUI.InputTextFlags_ReadOnly
• GUI.InputTextFlags_NoUndoRedo
• GUI.InputTextFlags_CharsScientific

• GUI.SelectableFlags_DontClosePopups
• GUI.SelectableFlags_SpanAllColumns
• GUI.SelectableFlags_AllowDoubleClick

• GUI.ComboFlags_PopupAlignLeft
• GUI.ComboFlags_HeightSmall
• GUI.ComboFlags_HeightRegular
• GUI.ComboFlags_HeightLarge
• GUI.ComboFlags_HeightLargest
• GUI.ComboFlags_NoArrowButton
• GUI.ComboFlags_NoPreview

• GUI.Col_Text
• GUI.Col_TextDisabled
• GUI.Col_WindowBg
• GUI.Col_ChildWindowBg
• GUI.Col_Border
• GUI.Col_BorderShadow
• GUI.Col_FrameBg
• GUI.Col_FrameBgHovered
• GUI.Col_FrameBgActive
• GUI.Col_TitleBg
• GUI.Col_TitleBgCollapsed
• GUI.Col_TitleBgActive
• GUI.Col_MenuBarBg
• GUI.Col_ScrollbarBg
• GUI.Col_ScrollbarGrab
• GUI.Col_ScrollbarGrabHovered
• GUI.Col_ScrollbarGrabActive
• GUI.Col_CheckMark
• GUI.Col_SliderGrab
• GUI.Col_SliderGrabActive
• GUI.Col_Button
• GUI.Col_ButtonHovered
• GUI.Col_ButtonActive
• GUI.Col_Header
• GUI.Col_HeaderHovered
• GUI.Col_HeaderActive
• GUI.Col_Column
• GUI.Col_ColumnHovered
• GUI.Col_ColumnActive
• GUI.Col_ResizeGrip
• GUI.Col_ResizeGripHovered
• GUI.Col_ResizeGripActive
• GUI.Col_PlotLines
• GUI.Col_PlotLinesHovered
• GUI.Col_PlotHistogram
• GUI.Col_PlotHistogramHovered
• GUI.Col_TextSelectedBg
• GUI.Col_TooltipBg
• GUI.Col_ModalWindowDarkening
• GUI.Col_DragDropTarget
• GUI.Col_NavHighlight
• GUI.Col_NavWindowingHighlight

• GUI.StyleVar_Alpha
• GUI.StyleVar_WindowPadding
• GUI.StyleVar_WindowRounding
• GUI.StyleVar_WindowBorderSize
• GUI.StyleVar_WindowMinSize
• GUI.StyleVar_ChildWindowRounding
• GUI.StyleVar_ChildBorderSize
• GUI.StyleVar_PopupRounding
• GUI.StyleVar_PopupBorderSize
• GUI.StyleVar_FramePadding
• GUI.StyleVar_FrameRounding
• GUI.StyleVar_FrameBorderSize
• GUI.StyleVar_ItemSpacing
• GUI.StyleVar_ItemInnerSpacing
• GUI.StyleVar_IndentSpacing
• GUI.StyleVar_ScrollbarSize
• GUI.StyleVar_ScrollbarRounding
• GUI.StyleVar_GrabMinSize
• GUI.StyleVar_GrabRounding
• GUI.StyleVar_ButtonTextAlign

• for ColorEdit3() / ColorEdit4() / ColorPicker3() / ColorPicker4() / ColorButton()
• GUI.ColorEditMode_NoAlpha
• GUI.ColorEditMode_NoOptions
• GUI.ColorEditMode_NoSmallPreview
• GUI.ColorEditMode_NoInputs
• GUI.ColorEditMode_NoTooltip
• GUI.ColorEditMode_NoLabel
• GUI.ColorEditMode_NoSidePreview
• GUI.ColorEditMode_AlphaBar
• GUI.ColorEditMode_AlphaPreview
• GUI.ColorEditMode_AlphaPreviewHalf
• GUI.ColorEditMode_HDR
• GUI.ColorEditMode_Uint8
• GUI.ColorEditMode_Float
• GUI.ColorEditMode_PickerHueBar
• GUI.ColorEditMode_PickerHueWheel
• GUI.ColorEditMode_RGB
• GUI.ColorEditMode_HSV
• GUI.ColorEditMode_HEX

• GUI.SetCond_Always
• GUI.SetCond_Once
• GUI.SetCond_FirstUseEver
• GUI.SetCond_Appearing

• GUI.DrawCornerFlag_TopLeft
• GUI.DrawCornerFlag_TopRight
• GUI.DrawCornerFlag_BottomLeft
• GUI.DrawCornerFlag_BottomRight

• GUI.FocusedFlags_ChildWindows
• GUI.FocusedFlags_RootWindow
• GUI.FocusedFlags_AnyWindow

• GUI.HoveredFlags_Default
• GUI.HoveredFlags_ChildWindows
• GUI.HoveredFlags_RootWindow
• GUI.HoveredFlags_AnyWindow
• GUI.HoveredFlags_AllowWhenBlockedByPopup
• GUI.HoveredFlags_AllowWhenBlockedByActiveItem
• GUI.HoveredFlags_AllowWhenOverlapped

• GUI.Dir_Left
• GUI.Dir_Right
• GUI.Dir_Up
• GUI.Dir_Down

• GUI.TreeNodeFlags_Selected
• GUI.TreeNodeFlags_Framed
• GUI.TreeNodeFlags_AllowItemOverlap
• GUI.TreeNodeFlags_NoTreePushOnOpen
• GUI.TreeNodeFlags_NoAutoOpenOnLog
• GUI.TreeNodeFlags_SDefaultOpen
• GUI.TreeNodeFlags_OpenOnDoubleClick
• GUI.TreeNodeFlags_OpenOnArrow
• GUI.TreeNodeFlags_Leaf
• GUI.TreeNodeFlags_Bullet
• GUI.TreeNodeFlags_FramePadding
• GUI.TreeNodeFlags_NavLeftJumpsBackHere
• GUI.TreeNodeFlags_CollapsingHeader