Active state is handled by main now. It appears that listitem and
treeexpander handled it manually (probably before main did). This
is unnecessary now, so let's remove it.
If the anchor is below the expanded item, the expanded item will
go out of view if there are sufficient children items. This is not
ideal, so make sure to scroll to the item to ensure it remains in
view.
With the introduction of the hide-expander property, I noticed that
the active state would persist in many cases because the release
signal was never emitted. In gtk3 tree expanders, expanded
on release. gtk4 expanded on press to match window explorer.
Per irc chat, the designers didn't have a strong preference
for press or release. In order to keep consistency and
fix this bug, let's move back to release.
Those property features don't seem to be in use anywhere.
They are redundant since the docs cover the same information
and more. They also created unnecessary translation work.
Closes#4904
Claim the pressed, released and canceled gestures
meant for the expander-icon of the TreeExpander.
This avoids selecting the row when expanding or collapsing it.
Closes#4199
Remove a boatload of "or %NULL" from nullable parameters
and return values. gi-docgen generates suitable text from
the annotation that we don't need to duplicate.
This adds a few missing nullable annotations too.
Document the role of the GtkTreeExpander, and the behaviour of the
expander button.
Additionally, improve the label of the expander button, by adding a
fixed "Expand" label, and setting the "labelled-by" relation to the
child of the GtkTreeExpander.
The intended use case of the "presentation" role is
| […] when an element is used to change the look of the page but does not
| have all the functional, interactive, or structural relevance implied
| by the element type, or may be used to provide for an accessible
| fallback in older browsers that do not support WAI-ARIA.
One of the examples is, literally:
| An element whose content is completely presentational (like a spacer
| image, decorative graphic, or clearing element);
Which fits perfectly for the GtkTreeExpander's "indent" builtin icon
widget.
This implements all the keybindings from GtkTreeView that can be
supported.
It does not implement expand-all, because supporting that means
causing the TreeListModel to emit lots of create_model vfuncs which in
turn would cause many items-changed signal which in turn would cause
many signal handlers to run which in turn would make "expand-all" very
reentrant, and I'm uneasy about supporting that.
For the mouse, just add a click gesture to the expander icon that toggles
expanded state.
It's quite a bit faster now, but the code is also a bit more awkward.
Pain points:
- GtkTreeListModel cannot be created in UI files because it needs
a CreateModelFunc.
Using a signal for this doesn't work because autoexpand wants to
expand the model before the signal handler is connected.
- The list item factory usage is still awkward. It's bearable here
because the list items are very simple, but still.
This is a container widget that takes over all the duties of tree
expanding and collapsing.
It has to be a container so it can capture keybindings while focus is
inside the listitem.
So far, this widget does not allow interacting with it, but it shows the
expander arrow in its correct state.
Also, testlistview uses this widget now instead of implementing
expanding itself.
