I know/think your guys are trying to keep the program as non technical as possible & sure tablet users can use a ruler but with a mouse one has to retry over and over till we get it.
The way I'd like to see it work is if you hold shift & click it draws a line (with what ever tool your using) from the last point you clicked/painted from before (& if hold ctrl it snaps to 15° angle). This is the way it's implemented in the GIMP (cant rememmber if PS has a similar technique).
Not the most importent thing but it work be a nice feature. :wink: