CollapsingHeader: IsVisible and IsOpen are BSubjects

[antongit]

After today's demo, the CollapsingHeader got IsOpen BSubject in addition to its IsVisible.

• IsVisible sets/gets if the header is displayed (user didn't click X button)
• IsOpen sets/gets if the header open (not collapsed)

@azeno would you please check the code here: https://github.com/vvvv/VL.ImGui/blob/main/src/VL.ImGui/Widgets/Tree/CollapsingHeader.cs

Here is the definition: https://github.com/ocornut/imgui/blob/873e9d35acb4d629a5ba06a312201edff8b9d0f6/imgui.h#L607

HowTo: HowTo Trees

[azeno]

Looks good, but why does it take many items? Should only be one Content input, no? Same for TabBar and probably some others. There should only be a few nodes which take many widgets.

[antongit]

The same goes for the TabItem. Its return value says if the Tab is selected (opened), its value says if the Tab is visible (at all) or closed (for example by pressing X).

[antongit]

CollapsingHeader: two Channels:

• IsVisible
• IsOpen

TabItem: two Channels:

• IsVisible
• IsActive

For both: boolean outputs of the same name. Channels represent the state of the items, and not the commands.

SetNextItemOpen - should we call this for each item, or only for only those that are true ( = shall be Open)?