Hello Martin,
Here is a script that did work for me in the past.
|view|
view := ROMondrianViewBuilder new.
view interaction on: ROMouseEnter do: [ :event |
view shape line color: Color blue.
view edgesFrom: [ :i | i // 2 ].
view raw signalUpdate.
].
view interaction on: ROMouseLeave do: [:event |
view raw allElementsDo: [ :el | el isEdge ifTrue: [el remove] ].
view raw signalUpdate].
view shape rectangle size: 20.
view nodes: (1 to: 20).
view gridLayout.
view open
I tried in the newest Roassal and it does not work (edges are not removed from the canvas). So, if you want to see it in action, you can do so with Roassal 1.147, which corresponds to (ConfigurationOfRoassal project version: '1.148') load.
I'll have a look into what broke this feature in latest Roassal.
Usman