ParamCheckList AV

We have users who sometimes have an AV in the TParamCheckList.ExtractWrapper. 
It's very random - has anyone seen this before?
The code where it's happening is:
function TParamCheckList.ExtractWrapper(Index: Integer): TObject;begin  result:=nil;  if (Index<0) then exit;  Result := TParamCheckListDataWrapper(inherited GetItemData(Index)); <-- I believe it happens here  if (Result <> nil) and (not (Result is TParamCheckListDataWrapper)) then    Result := nil;end;

Out of ideas and just wanted to see if anyone else has seen it.


Rhett Price

I'm not aware of other similar problem reports.

Is Index a valid value when it is being called?

Just stumbled upon this post when searching for known issues about a similar problem.

TParamCheckList is placed on a form. Param-class is DATE.
Manual date-entry is ok.
Opening date-picker, select a date => picker goes away
Click outside date => system freezes, looks like a recursion to me

Funny thing:
Windows Server 2008R2: all well
Windows Server 2012R2: can reproduce 100%

paramchklist.pas                      |paramchklist  |     |                               |1876[4]                        |
paramchklist.pas                      |paramchklist  |     |                               |2051[4]                        |
paramchklist.pas                      |paramchklist  |     |                               |2192[8]                        |
ParHTML.pas                           |ParHTML       |     |                               |2871[12]                       |
Vcl.Controls.pas                      |Vcl.Controls  |     |                               |7232[91]                       |
Vcl.Controls.pas                      |Vcl.Controls  |     |                               |10047[153]   

I have retested this here with the Parameter Controls demo for the entry showing the datepicker in the TParamCheckList control and I cannot reproduce a problem.

Can this be reproduced with the latest version of the TMS VCL UI Pack and this demo? If so, how exactly?

I tried with the latest ParamListBoxDemo but was not able to reproduce it.

AV in our application happens before ParamEditDone is called.

Form is quite complex, might be some botched eventhandling in our code.

IT had to provide my with an extra Windows 2012R2-machine as it works properly on 2008R2 and my local Windows 10.

Will provide more infos if I can track the cause down.