Please describe the problem:
GtkScaleButton tries to open the scale popup with +/- buttons in such a way that the slider button is right under the mouse pointer. But when the scale button is at a screen corner, this can't happen and mouse pointer is no more on top of the slider button. This is causing two problems:

1) When we do a short click on the button, the value is being set to min or max (sometimes) irrespective of the earlier value.

2) When we do a press an hold and try to drag, the old value is lost and the user can only set a new value. So slightly increasing/decreasing the value is not possible. 

Steps to reproduce:
1. Open an application that will place a GtkScaleButton in one of the corners of the screen (like totem in fullscreen mode).
2. Set the GtkScaleButton value to 50%
3. Short click on the button or in the long click mode, try to increase/decrease the value.


Actual results:
As described in the problem description.

Expected results:
A panel volume control like behavior is better than this.

Does this happen every time?
yes.

Other information:
I think idea to open the popup right under the mouse is not doing so well. When a user does a short click and the popup comes up, how does the user think of closing the popup? The button that opened the popup is not visible anymore covered by the popup itself. Clicking on the popup does not close it. No X button is available in the popup. The only way is find a vacant insensitive area in the application and click there (without the keyboard escape).