Define unambiguous Is{List,Text}Empty() in wxOwnerDrawnComboBox.

Like in wxComboBox itself, it's useful to provide these methods to avoid
problems with ambiguous IsEmpty(), inherited from both wxTextEntry and
wxItemContainer.

Closes #16618.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78015 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -82,6 +82,7 @@ All (GUI):
 - Add wxBitmap ctor from wxCursor.
 - Always disable wxWizard "Back" button on the starting page (pmgrace30).
 - Add wxUIActionSimulator::Select().
+- Add wxOwnerDrawnComboBox::Is{List,Text}Empty() methods.
 
 wxGTK:
 

include/wx/odcombo.h

@@ -315,6 +315,10 @@ public:
     virtual void Select(int n);
     virtual int GetSelection() const wxOVERRIDE;
 
+    // See wxComboBoxBase discussion of IsEmpty().
+    bool IsListEmpty() const { return wxItemContainer::IsEmpty(); }
+    bool IsTextEmpty() const { return wxTextEntry::IsEmpty(); }
+
     // Override these just to maintain consistency with virtual methods
     // between classes.
     virtual void Clear() wxOVERRIDE;

interface/wx/odcombo.h

@@ -199,6 +199,39 @@ public:
                 const wxString& name = wxComboBoxNameStr);
     //@}
 
+    /**
+        IsEmpty() is not available in this class.
+
+        This method is documented here only to notice that it can't be used
+        with this class because of the ambiguity between the methods with the
+        same name inherited from wxItemContainer and wxTextEntry base classes.
+
+        Because of this, any attempt to call it results in a compilation error
+        and you should use either IsListEmpty() or IsTextEmpty() depending on
+        what exactly do you want to test.
+     */
+    bool IsEmpty() const;
+
+    /**
+        Returns true if the list of combobox choices is empty.
+
+        Use this method instead of (not available in this class) IsEmpty() to
+        test if the list of items is empty.
+
+        @since 3.1.0
+     */
+    bool IsListEmpty() const;
+
+    /**
+        Returns true if the text of the combobox is empty.
+
+        Use this method instead of (not available in this class) IsEmpty() to
+        test if the text currently entered into the combobox is empty.
+
+        @since 3.1.0
+     */
+    bool IsTextEmpty() const;
+
     /**
         Returns index to the widest item in the list.
     */