croviax

Is there a way to draw straight lines using polygonal lasso like in Photoshop (Shift + Click) ?

i would just use then vector pen tool, having shift pressed would make verticals and horizontals, which I believe is what you want. Then hit -still with pen tool- the button in the top bar, at the left, which says "selection", will convert vectors to selection. You can assign a shortcut to pen, and another to lasso, or use defaults, if you want or need to work a lot with those two.(so no access to icons which can be faster if you have a good access to your keyboard and can deal with working with shortcuts (I do))