Qt Designer & Qt Widget Box are now greyed out in Eclipse

[CoopLoptex]

Hi,
I'm a newbie, and have (I think) successfully installed Qt integration, using Qt 4.8.0 into Eclipse Indigo. I successfully followed the basic AddressBook example which ran fine.

However, now when I click and open a .ui file, the QtDesigner menu and the Qt Widget Box remain greyed out. Qt C++ Properties remains active, so I can change properties of a ui form, but can't add any new widgets. I've tried a restart, and creating a new blank Qt project, but the problem remains.

I'm sure I'm missing something obvious, but it's not obvious to me, and I can't find any past solutions. Any suggestions?
Cheers,
Tom

[CoopLoptex]

Dear All,

After ignoring eclipse for a day and rebooting a few more times, this behaviour has disappeared, and everything is back to normal. If anyone has any suggestions as to why the menus were grey in the first place, that'd be interesting, but otherwise I'm back to happy programming! All the best,

Tom