Disabling close button in messageboxa with the use of sc_close [duplicate] - c

Question

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Disable X-Button Icon on the top of the right in Messagebox Using C++ Win32 API?
(4 answers)
Closed 2 years ago.
I had this problem for quite a while now.
In my message box, I have a cancel button. I don't want the close button to interfere because my cancel button does something, which shouldn't happen if I press the close button.
I used a loop-and-find trick, but when I open a folder that also has the same title as the message box, the code disables the close button of Explorer, which is very annoying.
This was what I used to disable the close button that also interferes with other windows that have the same title:
DWORD WINAPI CreateMessageBox(void *argr){
*(int*)argr = MessageBoxA( NULL,
"Time is past active hours\nPlease save your work\nSystem is shutting down in 1 minute.\n",
"Warning",
MB_OKCANCEL|MB_ICONSTOP|MB_SYSTEMMODAL );
return 0;
}
thread = CreateThread(NULL, 0, CreateMessageBox, &opt, 0, NULL);
while (!(msg = FindWindow(NULL, "Warning")));
style = GetWindowLongPtr(msg, GWL_STYLE);
SetWindowLongPtr(msg, GWL_STYLE, style & ~WS_SYSMENU);
WaitForSingleObject(thread, INFINITE);
But now, I read somewhere that there is this SC_CLOSE thing that also disables the close button exclusively to that window. How do I use it? I've gone through some posts about it, but none of them uses MessageBox() and that just overwhelms me.
Please, can somebody help me?

Answer 1

Your call to FindWindow() is not specifying a class name, thus it will find any top-level window with a matching title. In your case, an Explorer window. Provide the actual class name for the MessageBox window, which is "#32770", eg:
msg = FindWindow("#32770", "Warning")
However, there is a much more reliable approach that doesn't invoke searching window titles - get rid of the calls to CreateThread() and FindWindow() completely, and instead make the thread that calls MessageBox() use a local WH_CBT hook via SetWindowsHookEx() to catch the HWND that MessageBox() creates, then you can manipulate that window as desired, eg:
LRESULT CALLBACK MyCBTProc(int nCode, WPARAM wParam, LPARAM lParam)
{
if (nCode == HCBT_CREATEWND)
{
((CBT_CREATEWND*)lParam)->lpcs->style & ~WS_SYSMENU;
}
/* alternatively:
if (nCode == HCBT_ACTIVATE)
{
HWND hwnd = (HWND)wParam;
LONG_PTR style = GetWindowLongPtr(hwnd, GWL_STYLE);
SetWindowLongPtr(hwnd, GWL_STYLE, style & ~WS_SYSMENU);
}
*/
return CallNextHookEx(NULL, nCode, wParam, lParam);
}
...
HHOOK hHook = SetWindowsHookEx(WH_CBT, &MyCBTProc, NULL, GetCurrentThreadId());
opt = MessageBoxA(NULL,
"Time is past active hours\nPlease save your work\nSystem is shutting down in 1 minute.\n",
"Warning",
MB_OKCANCEL|MB_ICONSTOP|MB_SYSTEMMODAL);
if (hHook)
UnhookWindowsHookEx(hHook);
Alternatively, simply use TaskDialog() or TaskDialogIndirect() instead of MessageBox(). A Task Dialog does not have a close button in the title bar, unless you call TaskDialogIndirect() with the TDF_ALLOW_DIALOG_CANCELLATION flag enabled:
Indicates that the dialog should be able to be closed using Alt-F4, Escape, and the title bar's close button even if no cancel button is specified in either the dwCommonButtons or pButtons members.
TaskDialog(NULL, NULL,
L"Warning",
L"Time is past active hours",
L"Please save your work\nSystem is shutting down in 1 minute.",
TDCBF_OK_BUTTON | TDCBF_CANCEL_BUTTON,
TD_ERROR_ICON,
&opt);