SUMMARY After clicking using the middle button of the mouse to move the canvas it becomes impossible to drag any object through the use of the mouse pointer, although it's still possible to right click and to change the position value on the "Properties" panel. STEPS TO REPRODUCE 1. Open the program 2. Place any object from the "Palette" panel on the canvas 3. It will be possible to move the object by dragging it using the left mouse button 4. Click any point on the canvas using the middle mouse button 5. Now it's impossible to do step 3 I haven't tested on other platforms but it seems to be platform-independent and always reproducible.