Fix wxCommandProcessor::IsDirty() for unsaved unmodified case.

IsDirty() still returned true even after undoing all the commands which was
wrong, as there was nothing to save in this case.

Closes #15722.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75309 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -584,6 +584,8 @@ All (GUI):
 - Fix crash when setting invalid label ending with "&" (ZaneUJi).
 - Fix wxEditableListBox user data corruption when exchanging items
   in 64 bit builds (Tom Mettam, Rapid2D).
+- Fix wxCommandProcessor::IsDirty() return value which was wrong after undoing
+  all commands without saving (Neil Chittenden).
 
 wxGTK:
 

src/common/cmdproc.cpp

@@ -329,16 +329,11 @@ void wxCommandProcessor::ClearCommands()
 
 bool wxCommandProcessor::IsDirty() const
 {
-    if ( m_commands.empty() )
-    {
-        // If we have never been modified, we can't be dirty.
-        return false;
-    }
-
     if ( !m_lastSavedCommand )
     {
-        // If we have been modified but have never been saved, we're dirty.
-        return true;
+        // We have never been saved, so we are dirty if and only if we have any
+        // commands at all.
+        return m_currentCommand;
     }
 
     if ( !m_currentCommand )