Thanks for that advice @sjdorst! … I see, so perhaps what is going on is that, even though I drew my shape with the rectangle tool (instead of a individual lines), SketchUp will view my rectangle as individual lines until I add them to a group? Is that right?
Not quite right. Realize that all geometry in SketchUp consists solely of lines and faces, faces being defined by closed loops of coplanar lines. So yes, although the Rectangle tool appears to draw a rectangle, inside SketchUp, you have created 4 coplanar lines - and you’ve created a face since those 4 coplanar lines form a closed loop.
The reason you need to double click before making the group or component is that the first click selects the face, and the second click close enough in time to be a double click extends your selection to adjacent geometry - the 4 lines that make up the rectangle. Thus you now have 5 pieces of geometry selected: the face and the 4 lines of the rectangle. When you then make them a group or component, you’re telling SketchUp two essential things:
- Treat this set of geometry as a unit. and
- Don’t make assumptions about how this new entity interacts with the rest of the model. (Snapping to other geometry or guidelines while moving, rotating or scaling don’t count - they have more to do with alignment than with geometry interaction)
From this point on, it will take an explicit action on your part for your group/entity to interact with the rest of the model. Actions such as “explode” - which undoes the grouping, or “join faces” which can merge two groups.
And while your group can be moved, rotated and scaled as a single unit, to change the underlying geometry of the group (or component) you have to first “edit group” (or “edit component”).
Yes, what I’ve just gone over are fine points. But then, I am, by nature, a nitpicker!
Hope this helps!