unitialized mouseButtonDown variable in qgsmapcanvas.cpp

[smizuno]

in QgsMapCanvas::CanvasProperties the mouseButtonDown class member is not initialized. This causes the keyboard panning and zooming not to work until after a mouse click occurs on the map canvas. The behavior may depend on the platform -- I noticed this on Windows.

to demonstrate:

1. start QGIS
   
2. load a layer or project; the focus should be on the map canvas
   
3. use an arrow key to pan - nothing happens
   
4. click the mouse on the map
   
5. now an arrow key will pan
   

[jef]

fixed in r15013. Thanks.