The spinbox control to change the windowopacity property in UI designer should be updated.

Steps:

1. Create a new qt gui application project.
2. Open the .ui file with ui designer.
3. Focus on the mainwindow and try to change the windowopacity property in the property management list.

Issues found:
The value scope of the spinbox control to change the windowopacity property is not set. we can change the value form an very small navigate number to a very big positive number. but the suitable opacity property value is just from 0.00000 to 1.00000. we can't set the opacity property conveniently by operate the up and down button of the spinbox, but only set the real value by edit the Spinbox.