FIX: Assertion Failed Line 388 of Occmgr.cpp

   Debug Assertion Failed!
   Program: <app name>
   File: occmgr.cpp
   Line: 388
				

MORE INFORMATION

The MFC framework creates OLE controls placed on a dialog template resource, if any, by calling COccManager::CreateDlgControls. This function in turn makes a call to COccManager::CreateDlgControl to create a specific OLE control. The code present in CreateDlgControl attempts to setup the tab order of each OLE control after it is created, for which it calls CWnd::SetWindowPos, passing in the handle of the window that the control will be inserted after (in the code, this window is referred to as pWndAfter).

For a clear understanding of what would generate the above described ASSERT, consider the following reproducible scenario.

Steps to Reproduce the Assertion Failure

Create a dialog-based control container application, and place the following controls with the specified tab order in its main dialog template resource:

• MS-COMM OLE Control (or any invisible-at-run-time control) : 1
• GRID OLE control (or any control that is visible at run time) : 2
• Static control (or any standard Windows control) : 3
• GRID OLE control (or any control that is visible at run time) : 4

Because the MS-COMM OLE control is reparented to the desktop, the GRID control next to it in the tab order will be created and placed at the end of this dialog's child window list. Later when the framework creates the final GRID control, it tries to find the static control that should precede this GRID control in the Z order, by finding the next sibling window of the second GRID control. But because there is no next sibling window to the second GRID control, it returns NULL, which triggers the ASSERT.