Use wxString's empty() when checking if the string is (non-)empty throughout wx.

Instead of constructs such as if "( s.length() )" and "if (s.length() > 0)" use "if ( !s.empty() )" instead. Similarly for "if (s.length() == 0)" or "if ( s.IsNull() )", use "if ( s.empty() )".
No code changes intended except for a few instances where a construct like "if ( s.length() && wxFileExists(s) )" was changed to not check the length of the string and let wxFileExists handle such cases.



git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66728 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk1/combobox.cpp

@@ -744,7 +744,7 @@ void wxComboBox::Replace( long from, long to, const wxString& value )
 
     GtkWidget *entry = GTK_COMBO(m_widget)->entry;
     gtk_editable_delete_text( GTK_EDITABLE(entry), (gint)from, (gint)to );
-    if (value.IsNull()) return;
+    if ( value.empty() ) return;
     gint pos = (gint)to;
 
 #if wxUSE_UNICODE