Change shortcuts for Controlling Brush size and hardness using the Pen

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I'm working with HP Pen on HP x360, as Tablet - flipped the Keyboard to the back.

With HP Pen Control, its only possible to assign the Pen Buttons to ctrl OR to alt.  So it's not possible to press ctrl+alt. 

It woud be very useful and helpful, if one could chose for Example only to use strg with pen up and down and left and right to control brush size and hardness.