[FIX] missing generator expression for all(isinstance) check

Author: martinschwinzerl

qwt/plot_canvas.py

@@ -75,7 +75,7 @@ def drawRects(self, rects, count):
             # Pyside
             if isinstance(rects, (QRect, QRectF)):
                 self.border.list = [rects]
-            elif all(isinstance(rects, (QRect, QRectF)):
+            elif all(isinstance(r, (QRect, QRectF)) for r in rects):
                 if isinstance(rects, list):
                     self.border.rectList += rects
                 else: