I am having a slightly bizarre problem and am not sure what is happening so maybe someone else has seen it and could throw some light on the issue.
I have Qt 4.6.1 installed in Ubuntu 12.04 LTS x64 that is running as a virtual guest (VirtualBox) in Windows 7 x32.
Anyway… I have created a new widget and it won’t let me edit it or drag widgets onto it. It is almost like it is read-only. The icon when I drag is a circle with a line through it. I have seen mention of a drag-drop problem with Windows 7 but I have tried that fix and it doesn’t change anything.
Everything builds and runs, just cannot use the designer at all.
Hopefully this will help someone else who may have the problem as I have found a solution, although not an ideal one.
Basically it seems there might be an issue with the new Unity shell and Qt. I needed to change the shell to gnome and it works now.
In terminal:
Then logged out and switched to Gnome shell and now dragging-and-dropping works. I don’t know if the issue is within Virtualbox, Ubuntu 12.04 or Qt