[drakorg]

[attachment=7899:screenshot.1474840894.jpg]

'drakorg' wrote:

We are having trouble starting our application in Debug/WIN64 with FastMM4 FullDebugMode enabled, it raises an AV on this line of code:

Code:

function Ac_GetScrollWndFromHwnd(const AHandle: hwnd): TacScrollWnd;
begin
Result := TacScrollWnd(GetProp(AHandle, acPropStr));
end;

If we turn off FullDebugMode, it works.

If we switch to WIN32, even keeping FullDebugMode, it works.

AlphaControls is built from full sources packages, v11.16.

Do you have any idea what might be going on? We've never had any trouble with FastMM before, although we've never used the 64 bit version of the FullDebugMode dll before also.

Attached is a screenshot of the IDE, where you can see the call stack. That call is part of the creation of the main form, to give you some context, but please feel free to ask for more information if you need to.

Thank you.

Eduardo

[drakorg]

Looking deeper into it we've found that GetProp actually does return a value, and that it is casted to a TacScrollBar and returned successfully.

The problem appears one level up when it tries to access a property of that TacScrollBar object:

Code:

function Ac_GetScrollBarFromHwnd(const Handle: hwnd; const nBar: word): TacScrollBar;
var
sw: TacScrollWnd;
begin
Result := nil;
sw := Ac_GetScrollWndFromHwnd(Handle); // this one returns a value (apparently not a valid one)
if Assigned(sw) then // it IS assigned
case nBar of
SB_HORZ: Result := sw.sbarHorz; // however, it crashes when trying to access the TacScrollWnd object.
SB_VERT: Result := sw.sbarVert
end;
end;

Again, this only happens with FastMM FullDebugMode enabled on WIN64 platform. All other cases it works fine.

[Support]

Hello and thank you for this information.

I will research this issue very soon and hope to fix it in the nearest release.

[Author]

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