topic Modal Dialog X Button (Close Box) - How to properly handle or remove? in Archicad C++ API

Modal Dialog X Button (Close Box) - How to properly handle or remove?

Steve Sunny — Thu, 04 Dec 2025 15:35:12 GMT

I have a Modal dialog created with DGModalDialog and I'm having trouble with the X (close) button in the title bar.

GRC Definition:

'GDLG' 32500 Modal 0 0 680 640 "My Dialog" { /* [ 1] */ TextEdit 15 45 540 25 LargePlain 256 /* [ 2] */ Button 565 45 100 25 LargePlain "Search" /* [ 3] */ Button 565 600 100 30 LargePlain "Cancel" } Callback (simplified): static short DGCALLBACK MyDialogCallback(short message, short dialogID, short item, DGUserData userData, DGMessageData msgData) { switch (message) { case DG_MSG_INIT: return 0; case DG_MSG_CLICK: if (item == 3) { // Cancel button return 3; // Close dialog - THIS WORKS } break; case DG_MSG_CLOSE: return 3; // Close dialog } return 0; } // Called with: short result = DGModalDialog(resModule, 32500, resModule, MyDialogCallback, 0);

Problem:
- Clicking the Cancel button (item 3) correctly closes the dialog
- Clicking the X button in the title bar does NOT close the dialog

When X is clicked, I see DG_MSG_CLICK with item=2 first (my Search button!), then item=3, then DG_MSG_CLOSE. Even returning the button ID from all handlers doesn't close the dialog on X click.

Questions:
1. How do I properly handle the X button click on a Modal dialog?
2. Is there a way to remove just the X button while keeping the title bar? (I know Palettes have noClose flag, but Modal dialogs don't seem to have this option)

Using ArchiCAD API 28 on Windows.

Re: Modal Dialog X Button (Close Box) - How to properly handle or remove?

Sam Karli — Mon, 08 Dec 2025 12:48:49 GMT

Afaik the X button has a fixed number of 1.

'GDLG' SettingsPageId Modal 0 0 300 70 "Settings" { /* [ 1] */ Button 284 40 16 20 SmallPlain "" /* [ 2] */ LeftText 0 0 145 20 SmallPlain vCenter "Loglevel" /* [ 3] */ PopupControl 150 0 150 20 24 5 /* [ 4] */ LeftText 0 20 245 20 SmallPlain vCenter "Minimum number of edges to create an arc" /* [ 5] */ IntEdit 250 20 50 20 SmallPlain "0" "1000" } 'DLGH' SettingsPageId DLG_SettingsPageId { 1 "Close window" Button_OK 2 "Loglevel" LeftText_LogLev 3 "Select Loglevel" PopupControl_LogLev 4 "Minimum number of edges to create an arc" LeftText_ArcEdges 5 "Select Minimum number of edges to create an arc" IntEdit_ArcEdges }

// For PolygonReducer.grc #define SettingsPageId 32705 #define Button_OK 1 #define Button_Cancel 2 #define LeftText_LogLev 3 #define PopupControl_LogLev 4 #define LeftText_ArcEdges 5 #define IntEdit_ArcEdges 6

switch (message) { case DG_MSG_INIT: // ... break; case DG_MSG_CLICK: switch (item) { case DG_OK: result = item; break; } }

DG_OK and DG_CANCEL are defined in DGDefs.h.

Here I don't have a Cancel button, it is here only as a placeholder. Per its documentation:
"Modal dialogs have a so called default button which appears with a bold outline. The default button always should be the first dialog item in the dialog's item list (its item ID is DG_OK). Most modal dialogs also have a Cancel button which should be the second in the item list (its item ID is DG_CANCEL). Except for some special cases, pressing the ENTER or the ESC key has the same effect as clicking the default or the cancel button, respectively. For details see the dialog keyboard interface page.
---

DGModalDialog returns only if the modal dialog is closed. The user usually closes a modal dialog by clicking the OK or the Cancel button. The dialog callback function receives a DG_MSG_CLICK message with DG_OK or DG_CANCEL as the item parameter. On Windows, if the user clicks the close box in the caption the item parameter is DG_CANCEL (or DG_OK if there is no Cancel button in the dialog)."

Take this with a grain of salt, I also have my own UI problems, but this might help.

Re: Modal Dialog X Button (Close Box) - How to properly handle or remove?

Steve Sunny — Wed, 10 Dec 2025 04:57:06 GMT

Hi Sam,

Thank you for your help! Your solution worked perfectly.

Moving the Cancel button to Item 2 in the GRC resource file fixed the X button issue. The dialog now closes correctly when clicking the X button - no special workaround code needed.

For anyone else with this issue, the key is:
- Item 1 = Default/OK button
- Item 2 = Cancel button (X button triggers this automatically)

Thanks again!

Steve