Add virtual function to provide virtual wxListCtrl checkbox state

include/wx/listbase.h

@@ -433,6 +433,9 @@ protected:
     // return the text for the given column of the given item
     virtual wxString OnGetItemText(long item, long column) const;
 
+    // return whether the given item is checked
+    virtual bool OnGetItemIsChecked(long item) const;
+
     // return the icon for the given item. In report view, OnGetItemImage will
     // only be called for the first column. See OnGetItemColumnImage for
     // details.

interface/wx/listctrl.h

@@ -1271,6 +1271,13 @@ public:
         @param enable If @true, enable checkboxes, otherwise disable checkboxes.
         @return @true if checkboxes are supported, @false otherwise.
 
+        In a list control with wxLC_VIRTUAL style you have to keep track of the
+        checkbox state. When a checkbox is clicked (EVT_LIST_ITEM_CHECKED
+        or EVT_LIST_ITEM_UNCHECKED) you have to update the state and refresh
+        the item yourself.
+
+        @see OnGetItemIsChecked() RefreshItem()
+
         @since 3.1.0
     */
     bool EnableCheckBoxes(bool enable = true);
@@ -1312,7 +1319,7 @@ protected:
         The base class version always returns @NULL.
 
         @see OnGetItemImage(), OnGetItemColumnImage(), OnGetItemText(),
-             OnGetItemColumnAttr()
+             OnGetItemColumnAttr(), OnGetItemIsChecked()
     */
     virtual wxItemAttr* OnGetItemAttr(long item) const;
 
@@ -1370,6 +1377,17 @@ protected:
         @see SetItemCount(), OnGetItemImage(), OnGetItemColumnImage(), OnGetItemAttr()
     */
     virtual wxString OnGetItemText(long item, long column) const;
+
+    /**
+        This function @b must be overridden in the derived class for a control with
+        @c wxLC_VIRTUAL style that uses checkboxes. It should return whether the
+        checkbox of the specified @c item is checked.
+
+        @see EnableCheckBoxes(), OnGetItemText()
+
+        @since 3.1.2
+    */
+    virtual bool OnGetItemIsChecked(long item) const;
 };
 
 

src/common/listctrlcmn.cpp

@@ -261,6 +261,15 @@ wxString wxListCtrlBase::OnGetItemText(long WXUNUSED(item), long WXUNUSED(col))
     return wxEmptyString;
 }
 
+bool wxListCtrlBase::OnGetItemIsChecked(long WXUNUSED(item)) const
+{
+    // this is a pure virtual function, in fact - which is not really pure
+    // because the controls which are not virtual don't need to implement it
+    wxFAIL_MSG("wxListCtrl::OnGetItemIsChecked not supposed to be called");
+
+    return false;
+}
+
 int wxListCtrlBase::OnGetItemImage(long WXUNUSED(item)) const
 {
     wxCHECK_MSG(!GetImageList(wxIMAGE_LIST_SMALL),