Fix AUI tab close button size after DPI change in wxMSW

Reset close button size on DPI change to ensure that its size is
recomputed correctly using the new DPI when the tab is redrawn the next
time.

Closes #23400.

include/wx/aui/auibook.h

@@ -223,6 +223,7 @@ protected:
     void OnChar(wxKeyEvent& event);
     void OnCaptureLost(wxMouseCaptureLostEvent& evt);
     void OnSysColourChanged(wxSysColourChangedEvent& event);
+    void OnDpiChanged(wxDPIChangedEvent& event);
 
 protected:
 

include/wx/aui/tabart.h

@@ -113,6 +113,7 @@ public:
 
     // Provide opportunity for subclasses to recalculate colours
     virtual void UpdateColoursFromSystem() {}
+    virtual void UpdateDpi() {}
 };
 
 

include/wx/aui/tabartmsw.h

@@ -74,6 +74,8 @@ public:
         const wxAuiNotebookPageArray& pages,
         const wxSize& requiredBmpSize) override;
 
+    void UpdateDpi() override;
+
 private:
     bool m_themed;
     wxSize m_closeBtnSize;

src/aui/auibook.cpp

@@ -1003,6 +1003,7 @@ wxBEGIN_EVENT_TABLE(wxAuiTabCtrl, wxControl)
     EVT_CHAR(wxAuiTabCtrl::OnChar)
     EVT_MOUSE_CAPTURE_LOST(wxAuiTabCtrl::OnCaptureLost)
     EVT_SYS_COLOUR_CHANGED(wxAuiTabCtrl::OnSysColourChanged)
+    EVT_DPI_CHANGED(wxAuiTabCtrl::OnDpiChanged)
 wxEND_EVENT_TABLE()
 
 
@@ -1505,6 +1506,12 @@ void wxAuiTabCtrl::OnChar(wxKeyEvent& event)
         event.Skip();
 }
 
+void wxAuiTabCtrl::OnDpiChanged(wxDPIChangedEvent& event)
+{
+    m_art->UpdateDpi();
+    event.Skip();
+}
+
 // wxTabFrame is an interesting case.  It's important that all child pages
 // of the multi-notebook control are all actually children of that control
 // (and not grandchildren).  wxTabFrame facilitates this.  There is one

src/aui/tabartmsw.cpp

@@ -458,5 +458,9 @@ bool wxAuiMSWTabArt::IsThemed() const
         !(m_flags & wxAUI_NB_BOTTOM); // Native theme does not support bottom tabs
 }
 
+void wxAuiMSWTabArt::UpdateDpi()
+{
+    m_closeBtnSize = wxDefaultSize;
+}
 
 #endif // wxUSE_AUI && wxUSE_UXTHEME && !defined(__WXUNIVERSAL__)