diff --git a/Projects/Src/Shared.CommonFunc.Vcl.pas b/Projects/Src/Shared.CommonFunc.Vcl.pas index 1f3679d9..4d7d64a4 100644 --- a/Projects/Src/Shared.CommonFunc.Vcl.pas +++ b/Projects/Src/Shared.CommonFunc.Vcl.pas @@ -246,16 +246,14 @@ function AppMessageBox(const Text, Caption: PChar; Flags: Longint): Integer; { Always try to bring the message box to the foreground. Task dialogs appear to do that by default. - Without this, if the main form is minimized and then closed via the - taskbar 'X', a message box shown in its OnCloseQuery handler gets - displayed behind the foreground app's window, with no indication that a - message box is waiting. With the flag set, the message box is still shown - behind the foreground app's window, but the taskbar button begins blinking - and the main form is restored automatically. (These tests were done with - MainFormOnTaskBar=True and the message box window properly owned by the - main form. Don't run under the debugger when testing because that changes - the foreground stealing rules.) } + Due to Windows' protections against apps stealing the foreground, the + message box won't actually come to the foreground in most cases. Instead, + the taskbar button will flash. That's really all we need; the user just + needs to be made aware that a message box is awaiting their response. + (Note: Don't run under the debugger when testing because Windows allows + debugged processes to steal the foreground with no restrictions.) } Flags := Flags or MB_SETFOREGROUND; + if MessageBoxRightToLeft then Flags := Flags or (MB_RTLREADING or MB_RIGHT); @@ -297,6 +295,20 @@ function AppMessageBox(const Text, Caption: PChar; Flags: Longint): Integer; it's easier to get the message box back on top. (This problem doesn't occur when Application.MainFormOnTaskBar=True because the main form retains its WS_VISIBLE style while minimized.) + + UPDATE: Had to restrict the use of MB_TASKMODAL to only when + MainFormOnTaskBar=False is set to work around *another* VCL issue. + The above problem doesn't affect MainFormOnTaskBar=True so that should + be fine. + Details: When MainFormOnTaskBar=True and MessageBox is called with the + MB_TASKMODAL flag after the main form is created but before the main + form is shown, the message box appears on the screen but you can't + interact with it using the keyboard; keys like Enter and Escape have no + effect. The problem? The CM_ACTIVATE handler in TApplication.WndProc is + calling SetFocus with a NULL window handle. This erroneous SetFocus call + is only reached when the main form window is found to be disabled, which + only happens when MB_TASKMODAL is used. As noted above, non-visible + windows aren't disabled when only DisableTaskWindows is used. } if GetOwnerWndForMessageBox = 0 then begin ActiveWindow := GetActiveWindow; @@ -304,7 +316,9 @@ function AppMessageBox(const Text, Caption: PChar; Flags: Longint): Integer; try { Note: DisableTaskWindows doesn't disable invisible windows. MB_TASKMODAL will ensure that Application.Handle gets disabled too. } - Result := MessageBox(0, Text, Caption, Flags or MB_TASKMODAL); + if not Application.MainFormOnTaskBar then + Flags := Flags or MB_TASKMODAL; + Result := MessageBox(0, Text, Caption, UINT(Flags)); finally EnableTaskWindows(WindowList); SetActiveWindow(ActiveWindow);