I've got a slide out bluetooth external keyboard for my Samsung Galaxy S5. It's currently rooted and is running OmegaDroid as my ROM. I'd like to make it so that my modifier keys are "sticky", in that when I click the "shift" key, the next letter I type with be shifted. Right now, I have to hold the shift key down in order for the letter to be capitalized, and it is driving me up the wall. I much prefer the Droid 4 way of handling the shift key, as you don't have to do weird finger combinations or reach with your other thumb to get a letter to capitalize.
I'm totally rooted, and I'm happy with backing up my phone to try crazy things, as long as I can get this thorn out of my side :D.