Ability to change [left and right] margins row by row (with exclusion of some keys) OR

[Dani3I]

Goals:

• stretching the middle row ("asdfghjkl") to the width of the screen (in other words: horizontal starting position of letter "a" would be the same as starting position of the letter "q" and at the same time horizontal ending position of the letter "l" would be the same as ending position of "p". And all of the letters from this row would be stretched to fill unused space). [It is done that way in Fleksy keyboard].
• changing horizontal size of "shift" and "enter" keys, and then adjusting (stretching or squizing) all the other keys inside this row ("zxcvbnm") to fill all the possible space.

Implementation proposals:

• Instead of (or in addition to) currently existing way of changing the horizontal margin of whole keyboard, add a way to change margin of every row. Where margin of "zxcvbnm" row would mean position of "z" and "m" keys instead of "shift" and "enter" (and probably there should be distinction between left and right margin).
• other way of solving this problem (and probably more universal) would be to enumerate widths of every key. For example if I would write: 15, 10, 10, 10, 10, 10, 10, 10, 15 for "zxcvbnm" row it would mean that "enter" key would be 15% of total width "z" would be 10% etc.