Several small changes:
- Dropdowns: Populate `GridView` lazily (fixes#6865).
- Clear disconnected edges when editing node (fixes case 1 in #7018).
- Fix regression in node selection rendering (2nd bug in #6975).
- Update profiler docs. The hotkey to *prOfile without exiting* is now `Ctrl+Alt+O` (`Ctrl+Alt+P` has been requisitioned by the CB).
Node selection:
| Pre-`Rectangle` | This PR |
| --- | --- |
|  |  |
# Important Notes
- `Rectangle`: When `inset > border`, the extra space is now between the body and the border, not outside the border.
- More robust node layering logic. Now an inconsistent layer order cannot occur, even if something strange happens (like editing an expression and an edge at the same time).
- The dynamic drop down in the `drop_down` example scene doesn't show any entries before (or after) this, so I can't test the dynamic case.
Some small improvements relating to rendering:
- Add a debug option: `-debug.pixel-read-period`. This can be used to measure the performance impact of checking the pointer location on different hardware. [On my development box, it makes no difference to performance.] (Closes#5490).
- Unbind pixel pack buffers after each use. This is recommended practice. It has no performance impact on my machine, and allows SpectorJS to run (`-debug.enable-spector`). (Closes#5941).
Also, simplify the profiling CLI: the `profile.load-profile` and `profile.save-profile` options have been renamed to `profile.load`/`profile.save`; `profile.save` now has a default filename, so you can capture a profile at any time in Electron with Ctrl+Alt+P and it will be written to `profile.json`.
Start `project-manager` with following options to provide first 20s of the startup sequence:
```
$ project-manager --profiling-events-log-path=start.log --profiling-path=start.npss --profiling-time=20
```
once the `start.log` and `start.npss` files are generated (next to each other), open them in GraalVM's VisualVM:
```
$ graalvm/bin/jvisualvm --openfile start.npss
```
analyze.
