Reset current item in generic virtual wxListCtrl when items count changes.

This ensures that we don't end up with an invalid current item value, which
resulted in the asserts (see
http://thread.gmane.org/gmane.comp.lib.wxwidgets.general/80341) and possibly
worse.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75118 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/listctrl.cpp

@@ -3496,6 +3496,12 @@ size_t wxListMainWindow::GetItemCount() const
 
 void wxListMainWindow::SetItemCount(long count)
 {
+    // Update the current item if it's not valid any longer (notice that this
+    // invalidates it completely if the control is becoming empty, which is the
+    // right thing to do).
+    if ( HasCurrent() && m_current >= (size_t)count )
+        ChangeCurrent(count - 1);
+
     m_selStore.SetItemCount(count);
     m_countVirt = count;