Browser: Opera Mobile 11.50.14
Operating system: Maemo
Phone: Nokia N900

I can't actually replicate this on my Opera Mobile Nokia N900 emulator. What submit button is disabled for you?

The continue button will be disabled until you type in the input box. When you type in the box does it not enable itself?

The continue button, I mean, yes, and no, it doesn't enable itself.

The thing is though, I can't even see the Continue button while I'm editing, because while I'm editing the textarea occupies the entire main part of the window. In fact the only way I can get out of the textarea is to touch the Opera button and then go back again. So maybe it's something to do with that.

Sorry still a little confused.
I think you mean the cancel and continue buttons in the editor? The continue button is greyed out?

When you touch the done key on your keyboard after typing in the text area are you then able to locate the continue button? When you find it is it still greyed out? Where is it?

If you could provide screenshots/a video of this problem it will be clearer on what the problem is and how we might solve it. Is that something you can help us with?

To help with prioritisation of this bug:
For reference:

• For all edits 498,170 clicks on edit resulted in 310,692 clicks on continue resulting in 188,298 saves (37% of all clicks on edit result in a save, 62% of clicks on edit lead to clicking on continue).
• 2831 clicks on the edit button on Opera Mobile led to 941 clicks on continue and then 793 eventual saves [1] (28% of edit clicks result in a save, 33% of people that clicked edit then clicked continue).
  • The number of clicks on continue was almost half suggesting a problem

This could hint at this bug stopping a lot of potential contributions via Opera Mobile

[1] select count(*) from MobileWebEditing_5644223 where event_action = 'success' and event_userAgent LIKE '%Opera Mobi%'

Not enough details to continue. Also editor overlay is being redesigned thus we should revisit when those get pushed as this may fix / introduce other problems.