Add button to open the onscreen keyboard when a text input is selected, even if not using gamepad (for touchscreen control)

[Ferk]

I've set up steam to boot in Big Picture mode in my x86 tablet.
This is perfect because the UI is bigger and fits better. Also the tablet has a gamepad attachment which works great with the Big Picture mode.

With the success of the Nintendo Switch I wouldn't be surprised if we start seeing a rise of this type of gaming tablets.

However, the attachment is bulky and sometimes during my commute I only bring the tablet around. This still works very well for many games that are actually touchscreen compatible.

However, the Big Picture interface is still not optimal for touchscreens, particularly when having to enter login details or typing in any text input. Big picture does not let me open the Windows on-screen keyboard and there's no way to exit Big Picture and go back to normal mode within Steam in the big picture login interface (I guess with keyboard alt+enter would work... but there's no menu for mouse/touchscreen that lets me switch to the non-big picture interface from the login dialog).

Steam already has an on-screen keyboard built-in.. there should be a touch-friendly way to make that keyboard pop-up when in a text field. Whenever my gamepad attachment is set up I just need to press the A button on the textbox and the keyboard shows which is totally fine to use from the touchscreen afterwards.

It would be great if there was a button when a text input is selected that allowed us to open the same onscreen keyboard that shows when using a controller, which is actually touch-screen friendly.

There are many games that do support touchscreen quite decently. It's just the Steam interface the one that does not.