Hi,

to reproduce simply

- select a grammar which defines folding markers etc.

- type something which can be folded

- place the cursor just before the greyed three points indicator

- press e.g. ↩

it ends up like that:

[the problem - I can't even do an 'undo' and if I try to remove these CTRL char weird things happen]

or 

- place the cursor just after the three point indicator and start typing

- nothing to see but the typed chars are stored within the folded block

Cheers,

--Hans