WP widgets backend problem

I am having serious trouble with widgets in the backend:

when I drag’n’drop a widget onto a dynamic sidebar, the widget collapses and only ‘delete’,’close’ and ‘save’ buttons are visible. All form fields are hidden. When I save those “invisible options’, widget expands and displays all form fields correctly.

This happens only on my theme, when I switch the theme, widgets work correctly.

I tried to comment-out most code from functions.php and theme files (hooks/filters/etc.), but widget behaviour in the backend is the same.

Did anyone had this kind of problem?

My first step would be to try using Firebug of chrome developer tools to see the network activity when this happens and see if any php errors are being returned

It’s not that: ajax is executed properly (200 OK). I believe this is front-end only problem (jquery), but can’t figure it out

rvision_ said
It’s not that: ajax is executed properly (200 OK). I believe this is front-end only problem (jquery), but can’t figure it out

Have you got any widgets added with your theme code?

Removed them (1 of them, to be precise) but still the same.

rvision_ said
Removed them (1 of them, to be precise) but still the same.

ok, next step would be (if PHP is definately not returning any errors) to comment out all php files completely to see what happens. and i mean everything. Then gradually un-comment stuff.

Can’t believe this Fixed!

The functions.php had a block of commented PHP code – when I removed it, it worked normally

Reaper-Media thanks for your help anyway