DELPHI MessageDlg Call from DLL disrupts Control Focus - dll

Question

Recent upgrade to RAD XE8.
I have a dll with several MessageDLg calls e.g. Warning/Information etc e.g.
procedure Information(Msg: string); stdcall;
begin
MessageDlg(Msg,mtInformation, [mbOK],0);
end;
I noticed last week the following:-
If I double click on a grid with a handler
begin
Information("I am here"); //in the dll
ens
the message is displayed but when I click and the message box disappears I can no longer click on the grid (Mouse wheel does work but not the buttons) (no response). If I click on a second control and then back on the grid all is well again.
I tried adding to the DLL
uses VCL.Forms;
procedure Information(Msg: string); stdcall;
begin
Application.Handle := GetForegroundWindow;
try
MessageDlg(Msg,mtInformation, [mbOK],0);
finally
Application.Handle := 0;
end;
end;
to no avail.
I have established the following:-
ih my app
CanFocus; //DBGrid1
MessageDlg(Msg,mtInformation, [mbOK],0);
CanFocus; //Still DBGrid
but in my app (calling the MessageDlg in the DLL via the function Information())
CanFocus; //DBGrid1
Information('Hi ya');
CanFocus; //MAINFORM
CanFocus only added for debug purposes
So the first dblclick on the DBGrid calls Information but subsequent dblclicks are not detected in the VCL (messages are visible via Windows
Detective).
in VC.LDBGids TCustomDBGrid.AcquireFocus:
Focused is True the first time and False subsequently, until I click a second control and then back on the DBGrid.
Does his make the issue clearer?
TIA
Ephraim

Answer 1

Edit: Setting the global variable UseLatestCommonDialogs to False solved the problem!
I'm having the same issue and posted a question on Embarcadero Forum. I hope the answer help you:
That is because none of the HWNDs that belong to the EXE are being
used as the owner for the modal dialog window, so it can't restore
focus correctly when closed. That is why you have to click on the grid
again to regain focus.
Raymond Chen has a whole series of articles on his "Old New Thing"
blog on MSDN that discuss issues related to modal window ownership (or
lack of).
That is because calling MessageDlg() inside the EXE has access to the
EXE's TApplication and TForm HWNDs to use as modal dialog owners. A
DLL does not have that same access.
I would suggest getting rid of MessageDlg() inside the DLL altogether.
Call the Win32 MessageBox() or TaskDialog() directly instead, then you
can provide whatever HWND you need as the owner window.
Remy Lebeau (TeamB)