I have a recurring situation where the line
form.setfocus;
causes an AV in NTDLL. The form is visible, and were it not, I would
expect the usual "cannot focus a hidden or disabled window" exception.
Instead I get:
Access violation at address 7C918FEA in module "ntdll.dll". Write
address 00000010
'form' is a Tform (pointer), which is set correctly since the code
just before the .SetFocus call performs actions like
form.enabled:=true; which work correctly. The full code snippet is:
if assigned(parentform) then
begin
if not parentform.Visible then
debug_show('Form is not visible!'); //Temporary code
to debug NTDLL
parentform.Enabled:=yes; //Appears to work
parentform.SetFocus; //This line blows
up NTDLL
end;
The debug note doesn't show, and debugging confirms that the form is
visible when the .SetFocus call is made. This is 100% reproducible.
I also can't seem to trap it with Try-Except; I get the OS exception
instead of my code handling it. We're accustomed to working around
Windows bugs, but since I can't seem to trap this one, it's a problem.
This is fully-patched D6 under fully-patched XPSP2. Running the same
EXE under Win2000 results in a completely different symptom: Nothing
happens when that line is called, but when the ap closes (only if that
line was executed during the run), it generates the following:
The instruction at "0x0040402e" referenced memory at "0x05aad9e8".
The memory could not be "read".
Anyone seen this? It looks like Windows is getting confused, or has
lost a handle or something.
Thanks for any ideas,
-///Matt
