Gui/PD: Toggle body only from 3D view selection

[maxwxyz]

Supersedes #30218
PR #29110 changed that the spacebar always toggled the entire body when selected from the 3D view but that also changed for the space bar when a feature was selected in the tree view. Then, only in an active body, the features were toggled.

This changes the behavior:

• any selection from the 3D view always toggles the body (to fix the initial issue PD: Spacebar to toggle visibility of the parent body instead of the last visible feature #29110 fixed)
• any selection from the tree view (e.g. a feature) by mouse or keyboard always toggles the selection

There's a scenario where focus isn't reliable, if the user clicks in the tree to select, then clicks somewhere else in the UI without reselecting, then presses Space. This is very unlikely in normal usage.

Issues

Fixes #30216
Fixes #30221

Before and After Images

Bildschirmaufnahme.2026-05-17.um.10.46.21.mov

[maxwxyz]

@leoheck @entuland FYI

[entuland]

The video in the very first post looks good, I assume it's showcasing keyboard interaction.

Unfortunately I'm unable to test the PR before merging (no idea how to even test it, I could barely get the main branch pulled and built with pixi) plus I'm currently cut out from the Internet via my normal connection, forced to connect via USB tethering on a crappy mobile data plan.

If this fix also covers the context menu interaction (not illustrated by the video) retaining the old behavior, it would be functionally sound for me.

Apologies for the limited help I can provide here.

[FEA-eng]

Tested, fixes the issues and works as described