[Bug 8916] New: COMBOBOX editor stops working

[Wine Bugs]

http://bugs.winehq.org/show_bug.cgi?id=8916

Summary: COMBOBOX editor stops working
           Product: Wine
           Version: 0.9.40.
          Platform: Other
        OS/Version: other
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: wine-user
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]

with the code below combobox stops working and whatever I set to it using 
SetWindowTextW, it displays only the 1st character.

ComboHandle = CreateWindowExW(0, L"COMBOBOX", 0, 0x44210242, 55, 30, 190, 
21, ParentWnd, 0, HInstance, 0);
  ShowWindow(ComboHandle, SW_NORMAL);

// 3rd party library begins:
  EditHandle = GetWindow(ComboHandle, GW_CHILD);
  DefEditProc = GetWindowLongA(EditHandle, GWL_WNDPROC);
  SetWindowLongA(EditHandle, GWL_WNDPROC, DefEditProc);
// 3rd party library end.
  SetWindowLongW(EditHandle, GWL_WNDPROC, GetWindowLong(EditHandle, 
GWL_WNDPROC)); // this call is a fixup to trigger EditHandle into unicode and 
it works for me under Windows.

...
  SetWindowTextW(ComboHandle, L"Any Text"); // will display only "A"

I know that it's not that correct code but works FINE under Windows. 
Looks like   DefEditProc = GetWindowLongA(EditHandle, GWL_WNDPROC); is 
problematic because if I change GetWindowLongA to  GetWindowLongW it gets to 
work under Wine too but unfortunately, I can't change this pience of code 
because it is from 3rd party and comes pre-compiled.