Edit attributes of multiple objects at one time in the XML Editor

Summary:

Currently, if you select multiple objects the attributes editor pane is disabled: no attributes can be viewed, added, deleted or edited. It would be nice if you could work with the attributes of multiple objects at one time.

This would make it easier to work with a large number of similar objects. Currently I'm forced to repeat my actions on every object individually. This would also be consistent with visual interactions, such as picking a color, which does apply to all objects selected.

Steps to reproduce:

1. Open the XML Editor, with "Show Attributes"
2. Click on multiple objects

What happened?

Attributes panel is disabled

What should have happened?

Attributes panel should work with multiple objects:

• The Attributes pane shows a multiple view. List all attribute names across selected objects. If there value is not the same, it might suffice to show "Different Values" in a distinct way.
• If I delete an attribute, it deletes it across all the objects
• If I add an attribute it adds it to all the objects
• If I modify an attribute it replaces it in all objects
• Other attributes are left untouched

Version Info:

- Inkscape Version: 1.0.1 (1.0.1+r73)