one tap on slide should add option for textbox (tablet only)
In desktop version (on my Surface), one tap brings up a bunch of options, some of them not as important as others. But in mobile I only get the option to paste. I insert textbox quite often in my slides, and think you should add that option to the paste-icon that pops up when you tap the slide. This is how I do it on the desktop application.
This should perhaps only be done in tablet version. Seems like it would be annoying on the tiny screen of a phone.