Can't drop widgets to designer

Hi all

I have a problem with the designer of xamarin, i can't drop widgets!!!.

I have the following version:

Xamarin Studio Version 4.2.2 (build 2) Installation UUID: efg65rtg-6754-78ju-8165-5gy760hgy65 Runtime: Microsoft .NET 4.0.30319.18408 GTK+ 2.24.20 theme: MS-Windows GTK# (2.12.0.0)

Do somebody know if this it's a problem??

is there any way to fix this?

Any help will be very appreciated.

Regards.