I found 2 issues while testing MOBILE-3377.

Button unselected (Android and iOS)

1. In RTE, start writing some text.
2. Click the bold button. Check that the button is selected.
3. Write 1 character. Check that the character is bold, but now the button is unselected.
4. Write 1 more character. Check it is still bold, but the button is still unselected.
5. If you click bold again, cursor will got to the char you were on step 2.

Selection changed (Android only)

1. In RTE, write several paragraphs. In my case I had 4, and the last one had only one word.
2. Select the whole text.
3. Click the bold button. Check that the whole text becomes bold, but the last word is now unselected.