I am sure that following suggestions had been raised before, but it's good to keep them fresh
-keyword filter for windows, like Outliner have: for Materials, Components ..and Layers could have too. In Components is that 3dWarehouse search, but why can't we search on local library?
-details view for Materials, like Components have. Because hovering over each material to find its name it's not so accurate, often it have lags and it's slow process when you have 15-20 materials and some of them are too alike. And List view don't provide visual. And maybe in detailed view to see the size of texture tile?
-Clear Ruby Console built-in function -it would be nice, right?
I noticed that, when SU starts, first loads Getting Started toolbar, then unloads it and loads user's toolbars. What's the point to load something what's disabled? Just time and resource consuming.
-fix that bug which causes the right-click menu to gray-out sometimes.
-some way to be able to resize SketchUp window, without messing up all icons, Maybe a Lock Toolbar function Sometimes I need the sketchup window to be less than Full-Screen, and in this situations, if some icons would go out of screen would be OK, IF there would be a small (triangle) to access them in sort of vertical bar, like in MS Word, for example.
-and, YES... ConstructionLine Stipple FIX !