Happens in Firefox and chrome. Sony Xperia T. Android 4.3. The touch screen keypad disappears while I'm typing a post. Seems to happen when the forum saves a draft of the post. Also seems to be linked to browser cache, as emptying that in chrome fixes it for a while.
Tried switching from the forum custom skin back to default. Didn't help. Am making this post long to try and make it happen here.