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Forums » Prof-UIS Tech Support » CExtComboBox causing dialog to be sluggush Collapse All
Subject Author Date
Alastair Watts Jan 28, 2011 - 7:15 AM

I’ve a dialog with about 25 combo boxes on it.  When using CComboBox everything is fine.  Replacing them with CExtComboBox causes OnCmdMsg() to be called a lot which inturn slows the display & operation of the dialog considerably.

Any suggestions:


Technical Support Jan 31, 2011 - 11:19 AM

The problem is not with the CExtComboBox class. It’s just a repainted CComboBox version. The command updating code in your test app is extremely heavy. It should not be based on re-asking 30 combo boxes about selection. You should keep some enabled state flag in your dialog class and use it instead of CComboBoxTestDlg::DoCheck() method. This flag should be updated via handling the CBN_SELENDOK notification from combo boxes.

Alastair Watts Jan 31, 2011 - 6:33 AM

A test project has been sent.


Technical Support Jan 28, 2011 - 1:11 PM

We tried to test the behavior of CExtComboBox control using the following simplest possible test project:

But we saw only expected number of CBN_*** command notification sent by Windows Common controls rather than by by Prof-UIS. This sample app demonstrates the equal behavior of subclassed and unsubclassed combo box common controls. Could you reproduce the problem using this test project? You can comment/uncomment the SetAutoSubclassChildControls(); line of code to switch between CExtComboBox and unsubclassed combo box windows.