1. Disable virtual keyboard focus adjustment on Android
The default adjustment setting was causing the view to pan down in order
to adjust the focus on the text content.
We don't need any focus adjustment since we're using a fixed size window
for our application.
Documentation:
https://developer.android.com/reference/android/view/WindowManager.LayoutParams#SOFT_INPUT_ADJUST_NOTHING
2. Fix virtual keyboard height regression
Disabling virtual keyboard focus adjustement caused get_keyboard_height
to always return 0 because it was calculated when the view is resized.
In order to fix it, a PopupWindow is now created on top of the main view
and is set for focus adjustments so the keyboard size can be calculated
based on this popup without affecting the main view.
Depending on the device implementation, editor actions could be
received with different action ids or not at all for multi-line.
Added a parameter to virtual keyboards to properly handle single-line
and multi-line cases in all situations.
Single-line:
Input type set to text without multiline to make sure actions are sent.
IME options are set to DONE action to force action id consistency.
Multi-line:
Input type set to text and multiline to make sure enter triggers new lines.
Actions are disabled by the multiline flag, so '\n' characters are
handled in text changed callbacks.