Don't keep dangling pointers in other wxRibbonButtonBar members neither.

This should have been part of r75710: after deleting the button, also reset
any stored pointers to it.

Closes #15909.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75714 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/ribbon/buttonbar.cpp

@@ -515,6 +515,10 @@ bool wxRibbonButtonBar::DeleteButton(int button_id)
         {
             m_layouts_valid = false;
             m_buttons.RemoveAt(i);
+            if (m_hovered_button && m_hovered_button->base == button)
+                m_hovered_button = NULL;
+            if (m_active_button  && m_active_button->base  == button)
+                m_active_button = NULL;
             delete button;
             Realize();
             Refresh();