messages for combo box in a toolbar

Rob Gue -- rob.gue@gtri.gatech.edu
Sunday, June 02, 1996

NT 3.51, VC++ 2.1

I inserted a combo box in my frame's toolbar as described in the MFC sample
CTRLBARS (in a nutshell: reserve a space in the CToolBar instance for the
combo box with a separator and then create a CComboBox child window of the
toolbar in the reserved space).  Everything worked OK except for two things:

1) Enter and Escape don't work as they should when the combo box has the
focus (i.e. nothing happens when the user types in the edit portion of the
combo box and presses either one, nor do they hide the list box when it
displayed and the user presses either key).
   
2) The up and down arrow keys did not scroll the entries in the combo box.

Problem 2 was a result of there being accelerator keys defined for the
arrows keys (for scrolling the view).  To solve this, I overrode
PreTranslateMessage for my CComboBox-derived class, and check to see if the
message is WM_KEYDOWN with the vkey being either VK_UP or VK_DOWN.  If it
is, I call SendMessage to give myself the message, and then return TRUE (so
that processing of the key will stop).  Is this the best way to handle this
problem?

I am having more difficulty solving Problem 1.  The Enter and Escape keys
also seem to be processed by CMainFrame::PreTranslateMessage, although I
have not defined any accelerators for these keys.  So I tried the same
solution as for Problem 2 (i.e. overriding PreTranslateMessage and calling
SendMessage when receiving these messages), but this does not seem to work.
Does someone know what I need to do to accomplish this?.  I think that are
some points about MFC command routing and/or combo box controls that I am
not taking into consideration or am not aware of.

Thanks in advance (to everyone except Mike B., whom I shall thank after the
fact in the event of a reply :-),

rob.gue@gtri.gatech.edu

---

Greg D. Tighe -- gdt@eng.aisinc.com
Thursday, June 06, 1996

[Mini-digest: 2 responses]

> I inserted a combo box in my frame's toolbar as described in the MFC sample
> CTRLBARS (in a nutshell: reserve a space in the CToolBar instance for the
> combo box with a separator and then create a CComboBox child window of the
> toolbar in the reserved space).  Everything worked OK except for two things:
> 
> 1) Enter and Escape don't work as they should when the combo box has the
> focus (i.e. nothing happens when the user types in the edit portion of the
> combo box and presses either one, nor do they hide the list box when it
> displayed and the user presses either key).
>    
> Does someone know what I need to do to accomplish this?
> 
Rob,
	You need to subclass the edit control contained within the combobox, 
then override PreTranslateMessage() for the edit control.
To subclass the edit control, do something like this:

CWnd	*pEditWnd = pComboBox->GetWindow (GW_CHILD);

 if (NULL != pEditWnd)
  {
  m_CBoxEdit.SubclassWindow (pEditWnd->m_hWnd);
  }

m_CBoxEdit is a member variable CEdit-derived class.  From within 
this class you can override PreTranslateMessage() and check for 
WM_KEYDOWN keys where (wParam == VK_RETURN) ||
(wParam == VK_ESCAPE)

	-Greg Tighe
	Applied Intelligent Systems, Inc.
	Ann Arbor, MI
	gdt@aisinc.com
-----From: Dave Blatt/Newcastle/Computer Systems Australia/AU 

We do this slightly differently, and it works fine.  We just store the value 
when
we get a CBN_KILLFOCUS so that the enter key is not even necessary - this
is better for situations like when the user just clicks elsewhere on the screen
instead of pressing enter.  (Same behaviour as the Find combo box in
Developer Studio itself).  Then, to handle the enter key, we just pick it up in
the WMKEYDOWN handler and SendMessage a killfocus followed by a
setfocus.

If you also write a handler for CBN_SETFOCUS consisting of the one line
 SetEditCell(0,-1)
this will highlight the contents as the focus arrives.

Can send code snippets if above unclear,
Cheers
   DaveB and RogerO

PS Also, to see what is going wrong with your method, have you tried turning on
the Tools|MFC Tracer  main message dispatch to see what's actually happening?


PPS Your solution to (2) may not be the best way to go ... there's a KB article,
can't find it at the moment, will send more info.  I think there are other 
problems
to watch, like what happens when user presses delete key whilst in the combo.

---

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