Textbuttons now allow a selection too (like any textbutton in other UIs).
By default, on activating a textbutton, the entire button text is selected
when you enter the button. A single arrowkey or LMB click reveils the
cursor then. Here's more user notes:
LMB click: If inside the button, places the text cursor at the clicked
position. If outside the button, confirms/finishes editing
LMB drag: Selects the text between the start and end point of the drag.
Backspace: Deletes selected text, or backspaces a character
Shift Backspace: Deletes all, as before.
Delete: Deletes selected text or forward deletes a character
Shift LeftArrow: Extends the selection left
Shift RightArrow: Extends the selection right
LeftArrow: If there's a selection, move the cursor to the left edge of the
selection, otherwise move the cursor left a character.
RightArrow: If there's a selection, move the cursor to the right edge of
the selection, otherwise move the cursor right a character.
UpArrow/Home: Move the cursor to the beginning of the line
DownArrow/End: Move the cursor to the end of the line
Ctrl Left arrow and Ctrl Right arrow to jump between directory separators