Comment 15 for bug 1521518

W.r.t. “SDK might need adapting”, yes, this is largely a toolkit bug, because a toolkit is the most practical component to keep track of when “a text field becomes focused”. You can’t expect every app author to do this themselves, and you can’t expect users to learn+remember any alternative way of invoking the OSK.

An example flow would be:
a. You tap in a text field.
b. The toolkit says to the shell, “hey, I just focused a text field”.
c. The shell checks whether an external keyboard is connected; it is.
d. The shell checks whether the last character typed anywhere was with the OSK; it was.
e. The shell therefore opens the OSK, and tells the toolkit that it’s done so…

(…The shell also tells the toolkit what part of the window, if any, the OSK is obscuring. Then the toolkit says, “oh dear, that’s over top of the text field”, and scrolls the view to keep the field visible. But that’s another story.)