Mask tool not accurate?

Hi team,

I am having issues when using the mask tool, it doesn't seem to work here very accurately, I hope you can help me:

1)When I create a square shape and then I want to modify it to make it more a rectangle; for instance by moving two points at the same time, most of the time the lines get skewed.

HOW I DO THIS:

-I first select one point and then the second by pressing shift, without releasing the button of the mouse I start moving them to the intended position while holding shift.

-During the process is difficult to keep the lines straight, the tend to switch quickly between skewed and straight.

-Also, when trying to select the second point you see the hand instead of the cursor point, that makes the second selection very difficult.

-Finally, when you release the button of the mouse once you have them in the new position they tend to move slightly, sometimes I need to repeat the process several times to achieve what I want, which is not convenient at all.

2)I tried to use the pen tool to draw the squares but it doesn't seem to be possible to close the shape with all the lines straight.

Thanks for your help