Fix header text wrapping in sidebar

[bleakgrey]

Sometimes the text in sidebar header is wrapped even if there is room for the text. This PR expands the text box and adds a slight vertical padding to make the layout a bit more neat.

Before	After

[GeopJr]

Thanks for creating this PR!

Looks good to me, I just reverted the FIXME comment removal as it's about the (commented out) emoji label that currently looks like this:

[bleakgrey]

Ah I see. Packing emojis as separate widgets in a horizontal Box doesn't seem like a good idea - this approach doesn't work with word wrapping at all.

I think I had some research on drawing custom images directly on Gtk.Label widgets using pangocairo. I never managed to make a prototype, but maybe I could try again if I find it. Would you be interested in that?

[GeopJr]

Sure! Other alternatives I've considered are:

• Gtk.TextBuffer.insert_paintable https://valadoc.org/gtk4/Gtk.TextBuffer.insert_paintable.html
• Using webviews (which will be needed sooner or later if activitypub servers add more formatting options) which would also add support for animated emojis. But it depends on libsoup3.

[bleakgrey]

IMHO the former should be used in a pinch as it is not intended to be used in such quantities (GtkTextView makes more sense as a singular widget in the Composer dialog due to its rich editing capabilities).

As for the latter, webviews defeats the idea of using a native client. Besides, I can already tell that spawning a webview instance every time rich markup is expected (which is usually always and everywhere) will skyrocket the RAM usage, which is already abnormal. Might as well just use a browser 😄

Animated emojis is a valid point though. I'll see what we can do about them.

[GeopJr]

I see, thanks for the info!

For what it's worth, Fractal uses a custom label widget with children: https://gitlab.gnome.org/GNOME/fractal/-/blob/main/src/components/label_with_widgets.rs

[bleakgrey]

I absolutely love the idea of using a separate widget for each embedded image. Fractal uses Pango's shape attribute - exactly what I had in mind.

It seems to use these attributes to render custom glyphs in the Label's markup, get their pixel positions and use them for the embedded widgets. I think. Maybe. I wish I had more experience in Rust, it's mostly Greek to me :/