by Richard Russell, March 2007
If your program uses a Multiple Document Interface, by means of the MDILIB library, the background of the MDI client area is filled with the COLOR_APPWORKSPACE system colour, which by default is a mid-grey. Although you can change this colour in Windows Control Panel that will affect all applications, which you probably don't want to do.
It is possible to change the MDI client background colour just for your program by subclassing its window procedure. To do that you can use the following procedure:
DEF PROCsubclassmdiclient LOCAL E%, M%, O%, P% DIM P% 99 SYS "GetWindowLong", @hmdi%, -4 TO O% [OPT 2 .E% ; WM_ERASEBKGND push [^MDIBkgdCol%] call "CreateSolidBrush" mov edx,[esp+12] ; hDC = wParam sub esp,16 ; Room for RECT mov ecx,esp push eax ; for DeleteObject push eax ; for FillRect push ecx ; for FillRect push edx ; for FillRect push ecx ; for GetClientRect push @hmdi% call "GetClientRect" call "FillRect" call "DeleteObject" add esp,16 mov eax,1 ret 16 .M% cmp dword [esp+8],20 : jz E% : jmp O% ] SYS "SetWindowLong", @hmdi%, -4, M% ENDPROC
You should call this procedure immediately after initialising the Multiple Document Interface, as follows:
PROC_initmdi(hWindowMenu%) MDIBkgdCol% = &800000 PROCsubclassmdiclient
The MDI background colour will be set to whatever RGB value you load into MDIBkgdCol%, which in the above example is a dark blue.
If you want to change the MDI client colour whilst your program is running, you will need to use code similar to the following to force the background to be refreshed:
MDIBkgdCol% = &008000 SYS "InvalidateRect", @hmdi%, 0, 1