Notes on editing usability and design

I hate properties window showing and hiding all the time, distracting me from the actual mockup. Especially when I'm not going to fine tune the drawing and just throwing widgets here and there. I'd like to be able to dock it to the side of the canvas so that it just updates its content when I change selection. Common properties should be at top (like it is most of the time), so that when I change selection top properties are always in the same place.
If this were available, I would not need editing icons at the top. When docked to the right/left side, "quick add" could be just above the properties window, thus making some more vertical space for drawing.

Also, categories for gallery looks very weird and doesn't allow customization. I'd suggest assigning tags to widgets, show tag cloud and enable multiselection of tags. Gallery would then show all widgets which have at least one selected tags. User should be able to assign/reassign tags, like "Common" depends on user.

See mockup :)