ENH: Updated calibration UI for single-extruder printer

jira: none

Change-Id: I4e2d97f38699b13e2bced8f6a37c952f7903aa27
(cherry picked from commit 2e3a5e8ca71e3e9426412f8bd07b916f6be45aed)

src/slic3r/GUI/Widgets/AMSItem.cpp

@@ -2554,6 +2554,11 @@ void AMSPreview::OnLeaveWindow(wxMouseEvent &evt)
     // Refresh();
 }
 
+bool AMSPreview::IsSelected() const
+{
+    return m_selected;
+}
+
 void AMSPreview::OnSelected()
 {
     if (!wxWindow::IsEnabled()) { return; }