Unknown extended window style values from GetWindowLong and GetWindowInfo

Question

I am calling querying the extended window styles of a window using the GetWindowLog property and it is returning values in many cases that are not documented in msdn.

Particularly 0x00000800L and 0x00000100L or a combination of the two. Does anyone have information about these values, or a more complete list than what is documented on the msdn site?

Answer 1

I ran across this thread while looking for an answer to why this value changes when Microsoft Word "disappears" a window. I maintain an app that tracks the HWND values in order to do application sharing. This works well, but Microsoft Office applications often handle these in unusual ways. In this particular case, I found that if you do the following in Microsoft Word 2013:

1. Open two new documents in separate windows.
2. Save the HWND values for both windows.
3. Close one of the two windows.

Both HWND values will, when interrogated with the IsWindow, IsVisible, etc Windows functions, appear to be normal, still visible, etc. There's no way I can find to tell that one of the windows has been closed -- except this undocumented dwExStyle value. 0x800 will be 'on' in the window that's still visible, and 'off' in the window that isn't visible any more.

(BTW, I know you're not "supposed" to save HWND values this way -- but try tracking windows for sharing without saving this value -- not so easy!)

Answer 2

Since 0x00000100L is listed right on the Extended Window Styles page it is a little unclear to me if you mean the normal or extended style so I'll describe both.

Style:

• Dialog & old (user32) controls
  • 0xFFFF for control/dialog specific styles
• Common control:
  • 0x00FF is generally used by the shared common control styles (CCS_NORESIZE, CCS_TOP etc)
  • 0xFF00 for control specific styles, for a toolbar you would have TBSTYLE_LIST, TBSTYLE_TRANSPARENT etc

ExStyle:

• 0x00000100L=WS_EX_WINDOWEDGE
• 0x00000800L=Don't know, undocumented flag maybe (Edit: ReactOS has/had 0x00000800 as WS_EX_MAKEVISIBLEWHENUNGHOSTED, that does not mean that it has the same meaning on windows since ReactOS is not 100% compatible with windows)

Answer 3

Jeremy, this is just a bug of GetWindowInfo (for any OS after Win98: 2k, XP, Vista, Win7).

see http://rsdn.ru/forum/winapi/3362548.all.aspx ("WINDOWINFO.dwExStyle error")

try small tester therefrom: http://files.rsdn.ru/42164/wi_exstyle.zip

kero