CQ: replace a loop by a list comprehension in gmodeler.canvas (#4814)

it brings performance improvement and more readable code

gui/wxpython/gmodeler/canvas.py

@@ -440,12 +440,8 @@ def _onSelectShape(self, shape, append=False):
             shape.Select(False, dc)
         else:
             shapeList = canvas.GetDiagram().GetShapeList()
-            toUnselect = []
 
-            if not append:
-                for s in shapeList:
-                    if s.Selected():
-                        toUnselect.append(s)
+            toUnselect = [s for s in shapeList if s.Selected()] if not append else []
 
             shape.Select(True, dc)