Switch between drop-list and drop-down mode

After reading the article written by Robert Cremer , I realized that his version doesn't correctly draw the blue selection rectangle around the selected item within the combo box. Therefore, I took a different tack in the designing of my version of a class that allows you to programmatically switch a combo box between "drop-list" and "drop-down" mode.

To do this, I create an edit control that simulates the child edit of a real drop-down combo box. The included files have one CComboBox derived class with overrides on OnDropDown and OnCloseUp, and one CEdit derived class that takes care of the up/down arrows used no navigate in the combobox.

The only (let's say) tricky parts are:

• Making the edit selectable by mouse. I used ::SetWindowPos to put in in the front of the combo in the Z-order
• Making the combo selectable/not selectable by TAB. ModifyStyle(WS_TABSTOP,0) to remove, ModifyStyle(0,WS_TABSTOP) to add the combo to the tab order list.

Usage

• In your dialog, add a drop-list combobox
• Add a member variable to the dialog of the type CComboBox
• Modify the dialog's header file so that instead of the newly created combo box variable being declared as a CComboBox, it is declared as a CFineCombo.
• Now, update your dialog's code to include calls to SwitchToDrop(TRUE) (switches to drop-down) or SwitchToDrop(FALSE) (switches to drop-list) where appropriate.
• Delete the ClassWizard (.clw) file.
• Rebuild the ClassWizard file so that it contains the newly added CFineCombo class.

Downloads