Working with 2 canvas in specific size cause these problems:

- after changing color i have to reselect brush for painting one one canvas
- make rect selection causes other canvas to move top left corner and it too jumps there if i try to move it with space + mouse
- selections not possible on other canvas




Reproducible: Always

Steps to Reproduce:
1. open krita
2. create 2 canvas 800x400 size
3. zoom a step out on  the actuall one canvas (this canvas works as expected)
4. switch to other canvas you cant paint 
5. switch color causes brush dont work anymore (also selections dont work here anymore)
5b. selections tools not working, cant make a selection

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1. open krita
2. create 2 canvas 800x400 size
3. zoom a step out on  the actuall one canvas (this canvas works as expected)
4. make a rect selection
5. move the selection
6. switch to other canvas it is jumped top left and keep jumping there when try to move with space + mouse




Actual Results:  
The problem comes up after zoom a step out at one canvas.
Closing a canvas slove the problem.
Select other tool on canvas with the rect selection stops the other canvas jumping top left.

Expected Results:  
Work as expected :)

Win7 64bit uptodate
OpenGL on
4 Proc.
4 Gbyte
Nvdia GTX 660 (2Gbyte)