WM_CTLCOLORDLG

The WM_CTLCOLORDLG message is sent to a dialog box before the system draws the dialog box. By responding to this message, the dialog box can set its text and background colors by using the given display device context handle.

WM_CTLCOLORDLG 
hdcDlg = (HDC) wParam;   // handle of dialog box display context 
hwndDlg = (HWND) lParam; // handle of dialog box

Parameters

hdcDlg: Value of wParam. Identifies the device context for the dialog box.
hwndDlg: Value of lParam. Identifies the dialog box.

Return Values

If an application processes this message, it must return the handle of a brush. The system uses the brush to paint the background of the dialog box.

Default Action

The DefWindowProc function selects the default system colors for the dialog box.

Remarks

The system does not automatically destroy the returned brush. It is the application's responsibility to destroy the brush when it is no longer needed.

The WM_CTLCOLORDLG message is never sent between threads. It is sent only within one thread.

Note that the WM_CTLCOLORDLG message is sent to the dialog box itself; all of the other WM_CTLCOLOR* messages are sent to the owner of the control.

If a dialog box procedure handles this message, it should cast the desired return value to a BOOL and return the value directly. If the dialog box procedure returns FALSE, then default message handling is performed. The DWL_MSGRESULT value set by the SetWindowLong function is ignored.

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