Fix selection tool behavior in footprint viewer

The footprint viewer isn't an edit frame, so we need to access the
settings through the base frame type instead. Also, double click makes
no sense in the footprint viewer, and just leads to weird results
sometimes.

Fixes Sentry KICAD-7A2

pcbnew/tools/pcb_selection_tool.cpp

@@ -354,6 +354,13 @@ int PCB_SELECTION_TOOL::Main( const TOOL_EVENT& aEvent )
         {
             m_disambiguateTimer.Stop();
 
+            // Double clicks make no sense in the footprint viewer
+            if( frame && frame->IsType( FRAME_FOOTPRINT_VIEWER ) )
+            {
+                evt->SetPassEvent();
+                continue;
+            }
+
             // Double click? Display the properties window
             m_frame->FocusOnItem( nullptr );
 

pcbnew/tools/pcb_selection_tool.h

@@ -232,7 +232,12 @@ protected:
         return getViewControls();
     }
 
-    PCB_BASE_EDIT_FRAME* frame() const
+    PCB_BASE_FRAME* frame() const
+    {
+        return getEditFrame<PCB_BASE_FRAME>();
+    }
+
+    PCB_BASE_EDIT_FRAME* editFrame() const
     {
         return getEditFrame<PCB_BASE_EDIT_FRAME>();
     }