This patch to Delphi 6.02's Controls.pas fixes an AV issue with
combo boxes and Outlook Express; see:

http://groups.google.com/group/borland.public.delphi.vcl.components.using/browse_thread/thread/e012cea3ea1d258b

Delphi 2-5 have the same problem, but need a slightly different patch --
see VCL-Controls-D2D5-patch.txt.
Delphi 7 and later already incorporate an equivalent fix.

After applying the changes, recompile Controls.pas from the command
line as follows:

> c:\delphi\bin\dcc32 -$D- -$L- Controls.pas
> move Controls.dcu c:\delphi\lib


--- Controls.pas.orig Fri Feb 15 14:02:00 2002
+++ Controls.pas Tue Mar 19 21:04:58 2002
@@ -1743,14 +1743,20 @@
{ The global atom table is trashed when the user logs off. The extra test
below protects UI interactive services after the user logs off. }
function FindControl(Handle: HWnd): TWinControl;
+var
+ PID: DWORD;
begin
Result := nil;
if (Handle <> 0) then
begin
- if GlobalFindAtom(PChar(ControlAtomString)) = ControlAtom then
- Result := Pointer(GetProp(Handle, MakeIntAtom(ControlAtom)))
- else
- Result := ObjectFromHWnd(Handle);
+ if (GetWindowThreadProcessId(Handle, @PID) <> 0) and
+ (PID = GetCurrentProcessId) then
+ begin
+ if GlobalFindAtom(PChar(ControlAtomString)) = ControlAtom then
+ Result := Pointer(GetProp(Handle, MakeIntAtom(ControlAtom)))
+ else
+ Result := ObjectFromHWnd(Handle);
+ end;
end;
end;

@@ -2448,14 +2454,20 @@
// See comments for FindControl about global atom stability in service apps.

function IsDelphiHandle(Handle: HWND): Boolean;
+var
+ PID: DWORD;
begin
Result := False;
if Handle <> 0 then
begin
- if GlobalFindAtom(PChar(WindowAtomString)) = WindowAtom then
- Result := GetProp(Handle, MakeIntAtom(WindowAtom)) <> 0
- else
- Result := ObjectFromHWnd(Handle) <> nil;
+ if (GetWindowThreadProcessId(Handle, @PID) <> 0) and
+ (PID = GetCurrentProcessId) then
+ begin
+ if GlobalFindAtom(PChar(WindowAtomString)) = WindowAtom then
+ Result := GetProp(Handle, MakeIntAtom(WindowAtom)) <> 0
+ else
+ Result := ObjectFromHWnd(Handle) <> nil;
+ end;
end;
end;