[MSPAINT] Don't show error message twice (#5715)

- Reduce display of error message on IDM_EDITCOPYTO and IDM_EDITPASTEFROM.
- Introduce LockBitmap/UnlockBitmap mechanism for ImageModel and SelectionModel.
CORE-19181, CORE-19182

base/applications/mspaint/selectionmodel.cpp

@@ -528,3 +528,15 @@ void SelectionModel::SwapWidthAndHeight()
     m_rc.right = m_rc.left + cy;
     m_rc.bottom = m_rc.top + cx;
 }
+
+HBITMAP SelectionModel::LockBitmap()
+{
+    HBITMAP hbm = m_hbmColor;
+    m_hbmColor = NULL;
+    return hbm;
+}
+
+void SelectionModel::UnlockBitmap(HBITMAP hbmLocked)
+{
+    m_hbmColor = hbmLocked;
+}