GeDialog Manual


GeDialog is the base class for interface elements of Cinema 4D. An asynchronous (non-modal) dialog acts as a panel that can be added to the application layout or as a free floating window. In contrast a synchronous (modal) dialog blocks the application's main thread until it is closed. A custom dialog is added by creating a subclass of GeDialog. GeDialog is also the base class of iCustomGui which is used to create custom GUI elements for NodeData parameters.


A GeDialog based window is typically owned by a CommandData plugin. This CommandData stores and opens the dialog instance.

// This CommandData example opens and restores a GeDialog based window.
// g_geDialogID is the plugin ID of the CommandData plugin.
class OpenExampleDialog : public CommandData
INSTANCEOF(OpenExampleDialog, CommandData)
ExampleDialog _dialog;
// "Execute" function opens the dialog window
// open the dialog window if it is not already open
if (_dialog.IsOpen() == false)
_dialog.Open(DLG_TYPE::ASYNC, g_geDialogID, -1, -1, 400, 400);
return true;
// "RestoreLayout" is called to restore the dialog after a layout change
Bool RestoreLayout(void* secret)
return _dialog.RestoreLayout(g_geDialogID, 0, secret);
static OpenExampleDialog* Alloc() { return NewObjClear(OpenExampleDialog); }

The GeDialog is opened with GeDialog::Open(). The different types of dialogs are:

The GeDialog window can be closed with GeDialog::Close(). This will call GeDialog::AskClose() (see below).

GeDialog Based Classes

A custom window is created by implementing a subclass of GeDialog. This subclass can implement different virtual functions to define the layout and behaviour of the dialog.

Dialog setup:

// create the layout
Bool CreateLayout()
SetTitle("Example Dialog"_s);
AddEditNumber(1000, BFH_SCALEFIT, 0, 10);
// sets the timer to 1000 milliseconds
return true;
// Initialize internal data and set the values
Bool InitValues()
SetFloat(1000, 123.456);
return true;

Messages and Interaction:

// This "Command" function checks if the gadget with the ID 1000 was changed.
Bool Command(Int32 id, const BaseContainer& msg)
if (id == 1000)
ApplicationOutput("Gadget 1000 was changed.");
return GeDialog::Command(id, msg);
// This "Message" function checks if any interaction in the GeDialog starts or ends.
Int32 Message(const BaseContainer& msg, BaseContainer& result)
// messages are identified
// by the BaseContainer ID
switch (msg.GetId())
ApplicationOutput("Interaction start");
ApplicationOutput("Interaction end");
return SUPER::Message(msg, result);

Timed Actions:

// This "Timer" function is called depending on the value set with SetTimer()
void Timer(const BaseContainer& msg)

Read-Only Properties

It is possible to check these GeDialog properties:

It is also possible to read the pixel ratio of the current screen:

// This example adds a BitmapButton to the layout of the GeDialog.
// Depending on the pixel ratio a low-res or high-res bitmap file is loaded
// and applied to the BitmapButton.
void* const customGUI = AddCustomGui(1000, CUSTOMGUI_BITMAPBUTTON, ""_s, BFH_SCALEFIT, 300, 300, settings);
BitmapButtonCustomGui* const bitmapButtonGUI = static_cast<BitmapButtonCustomGui*>(customGUI);
if (bitmapButtonGUI)
// allocate bitmap
if (bitmap)
String filename = "";
// get pixel ratio
const Float pixelRatio = GetPixelRatio();
// check if Retina or not
if (pixelRatio == 1.0)
filename = "lowRes.png";
filename = "highRes.png";
// load bitmap (GetFullFilename() is just a custom utility function)
const String fullFileName = GetFullFilename(filename);
if (bitmap->Init(fullFileName) == IMAGERESULT::OK)
// store ratio
// apply to BitmapButton
bitmapButtonGUI->SetImage(bitmap, true, false);


Create Layout

The layout of a GeDialog - the arrangement of groups and gadgets - is defined in the implementation of GeDialog::CreateLayout(). This layout can be defined by creating the groups and gadgets individually or by loading a dialog resource file.

General functions to handle GeDialog gadgets are:

// This example loads a dialog layout from a resource file and edits it.
Bool CreateLayout()
// call default CreateLayout()
return false;
// load dialog from resource file
if (!LoadDialogResource(DLG_CUSTOM_DIALOG, nullptr, 0))
return false;
// set a different title
this->SetTitle("New Title"_s);
// disable a GUI element
this->Enable(IDC_CUSTOM_CHECKBOX, false);
return true;


GeDialog based windows contain a menu bar. This menu bar can contain various sub-menus and also any kind of gadget in a special sub-group.

Menus are created with:

Sub-menus are added with these functions:

Menu items are added with these functions:

// This example creates two sub-menus.
// submenu "Cinema Commands"
MenuSubBegin("Cinema 4D Commands"_s);
// add Cinema 4D commands
const Int32 saveAsCommandID = 12218; // "Save as" Command
const Int32 saveCommandID = 12098; // "Save" Command
// submenu "Dialog Commands"
MenuSubBegin("Dialog Commands"_s);
// add dialog commands
MenuAddString(ID_COMMAND_A, "Action A"_s);
MenuAddString(ID_COMMAND_B, "Action B"_s);
// set state
MenuInitString(ID_COMMAND_B, true, true); // set as checked

It is possible to add arbitrary gadgets to a special sub-group of the menu bar:

// This example adds a group to the menu bar.
// This menu group contains a button.
GroupBegin(1000, BFH_RIGHT, 2, 1, ""_s, 0);
AddButton(ID_MENU_BUTTON, BFH_SCALEFIT, 0, 10, "Button"_s);


The arrangement of elements of the dialog layout is defined with groups. Such groups can define rows and columns and can contain further sub-groups.

Groups are created with these functions:

// This example creates a group with two columns.
// The subgroup within the left column contains a tab group with two tabs.
// parent group with the whole width of the GeDialog
GroupBegin(100, BFH_SCALEFIT, 2, 0, ""_s, 0, 0, 300);
// left subgroup
GroupBegin(200, BFH_SCALEFIT | BFV_SCALEFIT, 1, 0, ""_s, 0, 0, 0);
// tab parent group within the left subgroup
// first tab group
GroupBegin(220, BFH_SCALEFIT | BFV_SCALEFIT, 1, 0, "Tab 1"_s, 0, 400, 300);
AddStaticText(221, BFH_SCALEFIT | BFH_LEFT, 0, 10, "Tab 1"_s, BORDER_NONE);
// second tab group
GroupBegin(230, BFH_SCALEFIT | BFV_SCALEFIT, 1, 0, "Tab 2"_s, 0, 400, 300);
AddStaticText(231, BFH_SCALEFIT | BFH_LEFT, 0, 10, "Tab 2"_s, BORDER_NONE);
// right subgroup
GroupBegin(300, BFH_SCALEFIT | BFV_SCALEFIT, 1, 0, ""_s, 0, 0, 0);
AddStaticText(301, BFH_SCALEFIT | BFH_LEFT, 0, 10, "Right subgroup"_s, BORDER_NONE);

The border style and spacing of groups can be defined with these functions:

// This example creates a group with space settings and a border.
GroupBegin(600, BFH_SCALEFIT, 2, 1, "Group"_s, BFV_BORDERGROUP_CHECKBOX, 0, 100);
GroupSpace(100, 0); // space between group elements
GroupBorder(BORDER_GROUP_IN); // group border
GroupBorderSpace(10, 10, 10, 10); // space around the group
AddButton(601, BFH_SCALEFIT | BFV_SCALEFIT, 0, 0, "Button A"_s);
AddButton(602, BFH_SCALEFIT | BFV_SCALEFIT, 0, 0, "Button B"_s);

If the group flag BFV_GRIDGROUP_ALLOW_WEIGHTS is set the user can change the width/height of group's columns/rows. The size of columns/rows is stored as "weights" which can be stored.

See also BFM_WEIGHTS_CHANGED in GUI and Interaction Messages Manual.

// This example creates a group with two columns.
// The width of these columns can be changed by the user.
GroupBegin(GROUP_LEFT, BFH_SCALEFIT | BFV_SCALEFIT, 1, 1, ""_s, 0);
AddStaticText(100, 0, 0, 10, "Left Column"_s, 0);
GroupBegin(GROUP_RIGHT, BFH_SCALEFIT | BFV_SCALEFIT, 1, 1, ""_s, 0);
AddStaticText(200, 0, 0, 10, "Right Column"_s, 0);
GroupWeightsLoad(WEIGHT_GROUP, _weights);

The content of a group can be flushed and replaced with new gadgets:

// This example flushes a layout group and fills it with new gadgets.
// flush group
// add new gadget
AddStaticText(101, BFH_SCALEFIT | BFH_LEFT, 0, 10, "New Element"_s, BORDER_NONE);
// update group
// This example flushes the group with the ID 1000 and adds new elements to it.
// begin layout change and store data
UpdateDialogHelper updateDialog = BeginLayoutChange(1000, true);
// add new elements to flushed group
AddStaticText(1100, BFH_SCALEFIT, 0, 10, "Add"_s, BORDER_NONE);
AddStaticText(1101, BFH_SCALEFIT, 0, 10, "new"_s, BORDER_NONE);
AddStaticText(1102, BFH_SCALEFIT, 0, 10, "elements"_s, BORDER_NONE);
// update group

A scroll group allows to scroll the content of a group using the mouse-wheel:

A scroll group must always contain another sub-group that stores the actual gadgets.

See also BFM_SETSTATUSBAR in Specific GUI Elements.

// This example creates a scroll group and fills it with multiple gadgets.
// layout group within the scroll group
GroupBegin(501, BFV_TOP | BFH_SCALEFIT, 1, 0, ""_s, 0);
// add gadgets
for (Int32 i = 0; i < 100; ++i)
AddCheckbox(502 + i, BFH_SCALEFIT | BFH_LEFT, 0, 10, "element"_s);
// This example gets the visible area of a scroll group and changes it.
Int32 x1 = NOTOK;
Int32 y1 = NOTOK;
Int32 x2 = NOTOK;
Int32 y2 = NOTOK;
// access the visible area of the scroll group
if (GetVisibleArea(scrollGroupID, &x1, &y1, &x2, &y2))
const Int32 height = y2 - y1;
SetVisibleArea(scrollGroupID, x1, 0, x2, height);

Gadget IDs

A gadget that is part of a GeDialog layout can be identified in two ways:

  • With a GadgetPtr. This GadgetPtr is returned by functions creating the gadget in question.
  • With the gadget ID. This gadget ID is used with the function that creates the gadget in question.
// This example creates two text edit fields.
// One edit field is edited using the C4DGadget pointer,
// the other using just the ID.
// add text edit field and store the C4DGadget pointer
C4DGadget* const textA = AddEditText(ID_TEXT_A, BFH_SCALEFIT, 0, 10, 0);
if (textA)
SetString(textA, "This is some text."_s);
// add text edit field
AddEditText(ID_TEXT_B, BFH_SCALEFIT, 0, 10, 0);
SetString(ID_TEXT_B, "This is some other text."_s);

Default Gadgets

Default GUI gadgets can be added to a GeDialog with these member functions:

Number related gadgets:

Text related gadgets:

Color related gadgets:



Further gadgets are:

// This example just adds some generic gadgets to the layout.
AddCheckbox(1000, BFH_SCALEFIT, 0, 10, "Checkbox"_s);
AddButton(2000, BFH_SCALEFIT, 0, 10, "Button"_s);
AddSeparatorH(0, BFH_SCALEFIT);
AddEditText(3000, BFH_SCALEFIT, 0, 10, 0);
// This example adds a list view to the GeDialog layout.
SimpleListView _listview;
Bool CreateLayout()
SetTitle("Listview Dialog"_s);
// add list view element to layout
AddListView(1000, BFH_SCALEFIT | BFV_SCALEFIT, 0, 0);
_listview.AttachListView(this, 1000);
return true;
Bool InitValues()
// configure listview columns
BaseContainer layout;
_listview.SetLayout(2, layout);
// don't allow multi selection
// fill with content
Int32 line = 0;
data.SetBool(CHECKBOX, true);
data.SetString(NAME, "Element A"_s);
_listview.SetItem(line, data);
++line; // increment ID
data.SetBool(CHECKBOX, false);
data.SetString(NAME, "Element B"_s);
_listview.SetItem(line, data);
// update
return true;

A multi-line text edit field can be created and configured with these functions:

See also Specific GUI Elements.

// This example creates a multi line edit field with Python syntax highlighting.
AddMultiLineEditText(4000, BFH_SCALEFIT, 0, 200, style);
// set some python code
SetString(4000, "import c4d\n\nprint(\"hello world\")\n"_s);
// set the cursor position at the beginning of the last line
SetMultiLinePos(4000, 4, 0);

Several gadgets can contain multiple child-elements, typically for selection purposes:

// This example creates a combo box and a combo button.
AddComboBox(5000, BFH_LEFT, 100, 10, false);
AddChild(5000, 0, "Child 0"_s);
AddChild(5000, 1, "Child 1"_s);
AddChild(5000, 2, "Child 2"_s);
AddComboButton(6000, BFH_LEFT, 100, 10, 0);
BaseContainer children;
children.SetString(0, "Child 0"_s);
children.SetString(1, "Child 1"_s);
AddChildren(6000, children);
// This example creates a combo box and defines the used icons.
// loading the icon data
IconData data1, data2;
GetIcon(Ocube, &data1);
GetIcon(Osphere, &data2);
// creating the combo box
// the address of the icon data is written into the String
AddComboBox(5001, BFH_LEFT, 100, 10, false);
const String iconData1Address = String::HexToString((UInt) & data1);
AddChild(5001, 0, "Cube &" + iconData1Address + "&");
const String iconData2Address = String::HexToString((UInt) & data2);
AddChild(5001, 1, "Sphere &" + iconData2Address + "&");

Further interaction with gadgets is typically done by sending messages to the gadget:

See also GUI and Interaction Messages Manual.

// This example creates a "Progress Bar" custom GUI element.
const Int32 flags = BFH_LEFT | BFV_FIT;
const BaseContainer settings;
AddCustomGui(10000, CUSTOMGUI_PROGRESSBAR, String(), flags, SizePix(100), SizePix(12), settings);
// This example sends a message to the progress bar custom GUI element.
m.SetFloat(BFM_STATUSBAR_PROGRESS, _someValue);
m.SetData(BFM_STATUSBAR_TINT_COLOR, Vector(0.0, 0.0, 1.0));
SendMessage(10000, m);


There is no default gadget to display an image (BaseBitmap) in a GeDialog. Two possible solutions are:

// This example creates a BitmapButtonCustomGui to present an image.
const Int32 flags = BFH_CENTER;
const Int32 width = SizePix(300);
const Int32 height = SizePix(50);
BaseContainer settings;
settings.SetBool(BITMAPBUTTON_BUTTON, false);
void* const customGUI = AddCustomGui(5050, CUSTOMGUI_BITMAPBUTTON, ""_s, flags, width, height, settings);
BitmapButtonCustomGui* const bitmapButtonGUI = static_cast<BitmapButtonCustomGui*>(customGUI);
if (bitmapButtonGUI)
bitmapButtonGUI->SetImage(buttonBitmap, true, false);

Custom GUI Elements

Further gadgets are implemented as custom GUI elements. Such custom GUI elements have to be created using their type ID.

A custom GUI is typically configured using a BaseContainer given to GeDialog::AddCustomGui(). Only the parameters accessible with the custom GUI class itself can be changed afterwards.
Custom GUI element instances are based on BaseCustomGui. Using this base class it is possible to further edit the instance.
Some "custom GUIs" are no real custom GUI elements but are hardcoded in the DescriptionCustomGui and cannot be used in a GeDialog (e.g. CUSTOMGUI_VECTOR).
// This example creates and configures a "Hyperlink" custom GUI element.
BaseContainer hlSettings;
hlSettings.SetBool(HYPERLINK_IS_LINK, true);
void* const customGui = AddCustomGui(11000, customGuiID, String(), BFH_SCALEFIT, 100, 50, hlSettings);
HyperLinkCustomGui* const linkGustomGui = static_cast<HyperLinkCustomGui*>(customGui);
if (linkGustomGui != nullptr)
const String linkTitle("MAXON");
const String url("");
linkGustomGui->SetLinkString(&url, &linkTitle);
// This example accesses a custom GUI element that is part of the GeDialog.
// The value presented in the GUI element is first set using the specific GUI element class.
// Alternatively one can also set the value using the BaseCustomGui base class.
// search for custom gui gadget
void* const customGUI = FindCustomGui(ID_GRADIENT, CUSTOMGUI_GRADIENT);
// cast into specific class
GradientCustomGui* const gradientGUI = static_cast<GradientCustomGui*>(customGUI);
if (gradientGUI)
// set data
AutoAlloc<Gradient> gradientData;
if (gradientData)
// set gradient data using the GradientCustomGui class function
// add a knot
GradientKnot firstKnot;
firstKnot.pos = 0.25;
firstKnot.col = Vector(1.0, 0, 0); // red
// set gradient data using the BaseCustomGui class function
// add a knot
GradientKnot secondKnot;
secondKnot.pos = 0.75;
secondKnot.col = Vector(0, 0, 1.0); // blue
// store as GeData
GeData geData;
// store as TriState
TriState<GeData> triStateData;
// set data of the GUI element


GeUserArea is the base class for all dialog gadgets. A subclass of GeUserArea defines a new custom gadget. Such a custom gadget can be added to the GeDialog.

See also GeUserArea Manual.

// This example adds a user area (that is owned by the GeDialog) to the layout.
C4DGadget* userarea = this->AddUserArea(12000, BFH_LEFT, 300, 100);
if (userarea)
this->AttachUserArea(_userArea, userarea);


It is possible to add a sub-dialog to a given GeDialog based window. Such a sub-dialog is based on SubDialog which in return is also based on GeDialog.

// This example adds a SubDialog based sub-dialog to the layout.
AttachSubDialog(&_subDialog, 14000);

For convenience it is possible to add a default group of gadgets to the dialog. This group can contain the standard buttons "OK" or"Cancel". See DLG.

// This example adds the generic "OK" and "Cancel" buttons to the layout.
// The "Command" function is called when a button is pressed.
Bool Command(Int32 id, const BaseContainer& msg)
switch (id)
// the "OK" button of a AddDlgGroup() group, IDC_CANCEL is the other
case IDC_OK:
ApplicationOutput("OK was pressed");
return true;

Pixel Size

For most gadgets it is possible to define the size of the gadget. To define this size one must use these functions to bake the pixel size:

  • SizePix(): Bakes the given pixel size.
  • SizeChr(): Bakes the given character count into a size.
  • SizePixChr(): Bakes the given pixel size and character count.
// This example creates a button with a height of 50 pixels.
AddButton(15000, BFH_SCALEFIT, 0, SizePix(50), ""_s);

Layout Flags

The position and behaviour of groups and gadgets is defined with these flags:

Horizontal alignment:

Vertical alignment:

// This example creates a group with three subgroups.
// The left and right subgroup have a fixed width.
// The center subgroup is scaled horizontally.
// the parent group with three columns
GroupBegin(20000, BFH_SCALEFIT, 3, 1, String(), BFV_GRIDGROUP_ALLOW_WEIGHTS);
// left group
GroupBegin(21000, BFH_LEFT | BFV_SCALEFIT, 1, 1, String(), 0, 100);
AddButton(21100, BFH_SCALEFIT | BFH_SCALEFIT, 0, 0, ""_s);
// center group
GroupBegin(22000, BFH_SCALEFIT | BFV_SCALEFIT, 1, 1, String(), 0);
AddButton(22100, BFH_SCALEFIT | BFH_SCALEFIT, 0, 0, ""_s);
// right group
GroupBegin(23000, BFH_RIGHT | BFV_SCALEFIT, 1, 1, String(), 0, 100);
AddButton(23100, BFH_SCALEFIT | BFH_SCALEFIT, 0, 0, ""_s);

Gadget Values

GUI elements are used to display values and to allow user interaction to change these values. For default GUI elements there are three kinds of functions to edit these values:

  • Plain getter/setter: Simple functions that allow to edit the value displayed in the given gadget.
  • Container getter/setter: Functions that access the value from a given BaseContainer.
  • TriState setter: Functions that set the value using the given TriState object (see TriState Manual)

Editing Boolean values:

Editing integer values:

Editing float values:

Editing Vector values:

Editing Time values:

Editing String values:

Editing Filename values: These functions just wrap around GeDialog::GetString() and GeDialog::SetString().

Editing Color values:

// This example adds different GUI elements to the layout and sets their values.
// add a text field and define the text
AddEditText(1000, BFH_SCALEFIT, 0, 10, 0);
SetString(1000, "Hello World"_s);
// add a number field and set the value using a TriState object
AddEditNumber(2000, BFH_SCALEFIT, 0, 10);
TriState<Int32> numberData;
SetInt32(2000, numberData);



A GeDialog receives messages from both its gadget and from the Cinema 4D GUI. They are sent to GeDialog::Message().

See GUI and Interaction Messages Manual.

// This example catches the event when the "F1" key is pressed in GeDialog::Message().
// check if this event was triggered by some keyboard interaction
// check if the "F1" triggered the event
ApplicationOutput("Pressed \"F1\" key."_s);
return true;

Interaction with Gadgets

When a gadget is changed it sends a message to the parent GeDialog. This message can be caught in GeDialog::Command().

See GUI and Interaction Messages Manual.

// This example adds a button to the layout.
AddButton(ID_BUTTON_ACTION, BFH_SCALEFIT, 0, 20, "Button"_s);
// The "Command" function is called when the button is pressed.
Bool Command(Int32 id, const BaseContainer& msg)
ApplicationOutput("Button pressed");

When a gadget is changed one might need to know the state of the mouse or keyboard when this happened.

// This example is executed in a GeDialog::Command() function.
// When the text gadget with the ID 1000 is changed its value is read.
// If the "Enter" key was pressed, the value is printed to the console.
if (id == 1000)
String value;
// get String value
if (GetString(1000, value))
// get state of the "Enter" key.
// check if "Enter" key is pressed
ApplicationOutput("Value: " + value);
// This example catches an interaction message in GeDialog::Message(). If the
// left mouse button is pressed more mouse events are processed via GeDialog::GetInputState().
// After the left mouse button is released all queued events are freed.
Int32 Message(const BaseContainer& msg, BaseContainer& result)
// messages are identified by the BaseContainer ID
switch (msg.GetId())
// interaction event
// check if mouse event
// check if left mouse button
// save initial start position
Int32 xPos = msg.GetInt32(BFM_INPUT_X);
Int32 yPos = msg.GetInt32(BFM_INPUT_Y);
// loop and process queued events
// check if left mouse button is still pressed
// get coordinates
const Int32 currentX = res.GetInt32(BFM_INPUT_X);
const Int32 currentY = res.GetInt32(BFM_INPUT_Y);
// compare coordinates
const Bool xPosChanged = currentX != xPos;
const Bool yPosChanged = currentY != yPos;
if (xPosChanged || yPosChanged)
ApplicationOutput("Mouse dragged and moved");
xPos = currentX;
yPos = currentY;
// delete all other events that might have occurred in the meantime
return true;
return SUPER::Message(msg, result);

Drag and Drop

The user can drag and drop various elements onto a GeDialog. The GeDialog is informed about this event through messages sent to GeDialog::Message(). These functions are used to react to these messages:

See also Drag and Drop.

// This example catches a Drag&Drop message.
// If the dragged element is a C4DAtom the name of the element is displayed in a text field.
Int32 Message(const BaseContainer& msg, BaseContainer& result)
// messages are identified by the BaseContainer ID
switch (msg.GetId())
// Check if the drag is over a certain gadget
if (CheckDropArea(ID_TEXT_NAME, msg, true, true))
void* object = nullptr;
Int32 type;
// get the dragged element
if (!GetDragObject(msg, &type, &object))
return false;
// if the drag is finished set the text gadget
const Bool typeIsAtom = type == DRAGTYPE_ATOMARRAY;
const Int32 isFinished = msg.GetInt32(BFM_DRAG_FINISHED);
if (typeIsAtom && isFinished)
const AtomArray* const atomArray = static_cast<AtomArray*>(object);
// check if the AtomArray can be accessed and if it contains any objects
if (atomArray && atomArray->GetCount() > 0)
C4DAtom* const atom = atomArray->GetIndex(0);
// check if the given C4DAtom is a BaseList2D element
if (atom && atom->IsInstanceOf(Tbaselist2d))
BaseList2D* const baselist = static_cast<BaseList2D*>(atom);
SetString(ID_TEXT_NAME, baselist->GetName());
return true;
return SetDragDestination(MOUSE_POINT_HAND);
return SetDragDestination(MOUSE_FORBIDDEN);
return SUPER::Message(msg, result);

Core Messages

A GeDialog can also receive core messages. These messages are sent to inform the dialog about global events e.g. when something in the active document changed. The messages are sent to GeDialog::CoreMessage().

See also GUI and Interaction Messages Manual and Core Messages Manual.

// This example catches the core message EVMSG_CHANGE and re-initializes the dialog's values.
// This is typically done to update GUI elements that correspond to certain scene elements.
Bool CoreMessage(Int32 id, const BaseContainer& msg)
switch (id)
// check if this core message is new
if (!CheckCoreMessage(msg))
return GeDialog::CoreMessage(id, msg);
Bool InitValues()
// set default value
SetString(1000, "---"_s);
// access active document and object
if (!doc)
return true;
BaseObject* const object = doc->GetActiveObject();
if (!object)
return true;
// set string value
SetString(1000, object->GetName());
return true;

GeDialog Parent

A GeDialog can be the base of a sub-dialog or a custom GUI element. In this case it must send messages to a parent dialog. The typical use case is a custom GUI element (based on CustomGuiData, iCustomGui) that has to inform the parent dialog that a stored value has changed.

// This example sends a message from a GeDialog (iCustomGui)
// to the parent GeDialog to inform about change of stored value.
// construct the message
message.SetInt32(BFM_ACTION_ID, GetId());
message.SetData(BFM_ACTION_VALUE, _value);
// send the message



These utility functions allow to access the dimensions of a gadget or to transfer given coordinates into various spaces:

// This example catches the event when the button with the ID 4000 is pressed.
// The dimensions of the button are accessed and transferred into screen space
// so a pop up menu can be displayed beside it.
if (id == 4000)
// get button dimensions
Int32 x, y, w, h = 0;
GetItemDim(id, &x, &y, &w, &h);
// construct position of the pop up menu
x += w;
Local2Screen(&x, &y);
// define pop up menu
bc.InsData(5159, "CMD"); // cube
bc.InsData(0, String());
bc.InsData(5160, "CMD"); // sphere
// show pop up menu
ShowPopupMenu(Get(), x, y, bc);


Color related functions are:

// This example edits the color of the text gadget with the ID 1000.
// The text color is set to red.
SetDefaultColor(1000, COLOR_TEXT_EDIT, Vector(1.0, 0.0, 0.0));

Further Reading