+ /*
+ The native control provides a great variety in the events it sends in
+ the different selection scenarios (undoubtedly for greater amusement of
+ the programmers using it). For the reference, here are the cases when
+ the final selection is accepted (things are quite interesting when it
+ is cancelled too):
+
+ A. Selecting with just the arrows without opening the dropdown:
+ 1. CBN_SELENDOK
+ 2. CBN_SELCHANGE
+
+ B. Opening dropdown with F4 and selecting with arrows:
+ 1. CBN_DROPDOWN
+ 2. many CBN_SELCHANGE while changing selection in the list
+ 3. CBN_SELENDOK
+ 4. CBN_CLOSEUP
+
+ C. Selecting with the mouse:
+ 1. CBN_DROPDOWN
+ -- no intermediate CBN_SELCHANGEs --
+ 2. CBN_SELENDOK
+ 3. CBN_CLOSEUP
+ 4. CBN_SELCHANGE
+
+ Admire the different order of messages in all of those cases, it must
+ surely have taken a lot of effort to Microsoft developers to achieve
+ such originality.
+ */
+ switch ( param )
+ {
+ case CBN_DROPDOWN:
+ // we use this value both because we don't want to track selection
+ // using CB_GETCURSEL while the dropdown is opened and because we
+ // need to reset the selection back to it if it's eventually
+ // cancelled by user
+ m_lastAcceptedSelection = GetCurrentSelection();
+ break;
+
+ case CBN_CLOSEUP:
+ // if the selection was accepted by the user, it should have been
+ // reset to wxID_NONE by CBN_SELENDOK, otherwise the selection was
+ // cancelled and we must restore the old one
+ if ( m_lastAcceptedSelection != wxID_NONE )
+ {
+ SetSelection(m_lastAcceptedSelection);
+ m_lastAcceptedSelection = wxID_NONE;
+ }
+ break;
+
+ case CBN_SELENDOK:
+ // reset it to prevent CBN_CLOSEUP from undoing the selection (it's
+ // ok to reset it now as GetCurrentSelection() will now return the
+ // same thing anyhow)
+ m_lastAcceptedSelection = wxID_NONE;
+
+ {
+ const int n = GetSelection();
+
+ wxCommandEvent event(wxEVT_COMMAND_CHOICE_SELECTED, m_windowId);
+ event.SetInt(n);
+ event.SetEventObject(this);
+
+ if ( n > -1 )
+ {
+ event.SetString(GetStringSelection());
+ InitCommandEventWithItems(event, n);
+ }
+
+ ProcessCommand(event);
+ }
+ break;
+
+ // don't handle CBN_SELENDCANCEL: just leave m_lastAcceptedSelection
+ // valid and the selection will be undone in CBN_CLOSEUP above
+
+ // don't handle CBN_SELCHANGE neither, we don't want to generate events
+ // while the dropdown is opened -- but do add it if we ever need this
+
+ default:
+ return false;
+ }
+
+ return true;