I've been trying to edit an Inkscape diagram I've created; there's a segment I'd like to separate from the rest of the shape it belongs to and turn it into a separately-editable shape (for which I can adjust the fill and stroke separately from the rest of its currently associated shape).
So what I did with an object with tons of nodes (traced bitmap) is:
- Duplicate the Object (Ctrl+D)
- Enter "Edit by paths" (Key F2)
- Select a rectangular region of the nodes by holding the Shift Key and selecting with the mouse
- Invert the selection of nodes using Alt+!
- Press Del to remove the unwanted nodes.
If you don't manage to select all nodes in one rect, just keep holding the Shift key to add another rectangular selection of nodes to the already selected ones.
- Select your shape and switch to edit path by nodes.
- Create two new nodes on the border of your shape where you want to detach it by double clicking at the respective position.
- Select those nodes and break path at selected nodes.
- Path → Break Apart.
- If this produces more than two objects, deselect the part you want to detach and Path → Combine.
- If you want the objects to be “closed” at the cut, select a single object, edit path by nodes, mark the two nodes where you cut the path and join selected endnodes with a new segment. (This may also fix some weird issues, if the former step was necessary.)