Added panning to GL view, added action for resetting angles, zoom and pan

Use mouse wheel for zooming instead of pressing the mouse button and detecting vertical movement.

Show an error message box when main file loading fails.

A saving failure is a critical error, not a warning and should be drawn as such

Warn for save failures with the save and save as actions, also provide with a button to save the file under a different name.

Keep track of when the file was last saved and warn if there are unsaved changes when the application is closing.

Grid icons..

(0) -100 -30 -10 -7 +7 +10 +30 +100 +300 +1000 tip

mercurial