The debug version of the ActiveX control causes an ASSERT in file Ctlcore.cpp, at the end of COleControl::CreateControlWindow, on or near line 662.
This problem occurs only when you build an .exe from Visual Basic 6.0 and run it from outside the Visual Basic development environment.
Microsoft Visual Basic executables do not initialize the common control library (Comctl32.dll) by default, resulting in the CreateEx call failing in COleControl::CreateControlWindow. Calling GetLastError() gives 0x0000057F - Cannot find window class, which indicates the common control library needs to be explicitly initialized.
Inside the InitInstance of your ActiveX control, make a call to:
This ensures that Comctl32.dll is loaded and initialized, regardless of the container the control is running in.
Instead of calling InitCommonControls from the control's code, you can also call it directly from the Visual Basic client application:
Make a General declaration for the corresponding Form; for example:
Private Declare Sub InitCommonControls Lib "comctl32.dll" ()
Add a call to:
in the Form_Load method.
In some situations, this might be too late to initialize the common controls library. Therefore, it is recommended to add this call in the InitInstance of the control.
This behavior is by design.
Steps to Reproduce Behavior
Using Visual C++, MFC ActiveX control wizard, create a default ActiveX control.
In the Control Settings section of the AppWizard (Step 2 of the Visual C++ 6.0 AppWizard), in the window class to subclass, choose one of the following: msctls_hotkey32, msctls_progress32, msctls_statusbar32, msctls_trackbar32, msctls_updown32, SysAnimate32, SysHeader32, SysListView32, SysTabControl32, or SysTreeView32.
Build the control.
Open Microsoft Visual Basic 6.0 and create a new Standard Exe project.
From the Project menu, click Components, and select the control that you just created using Microsoft Visual C++.
Select this control and draw that in the Form window.
From the File menu, click Make Project.exe, and build the exe.