There is some possibility Ubuntu GNOME will switch to LSC until gnome-software (and its archive backends) are ready.
For that it would be nice to have LSC looking more like a native GNOME app. Joern already added basic GtkHeaderBar support but it needs some tweaking to fit in better. This is just a wishlist to track items that could use attention. Some are just simple tweaks others are more wish list-y
- App title is not normally shown in the gtkheaderbar, since it gets shown in the shell top-bar (App menu)
- There should be a seperator between toolbar and window controls
- background color of toolbar (LSC tabs) doesnt match the headerbar when LSC is focused
- Most (if not all) icons in GNOME app headerbars use symbolic versions
- The toolbar currently requires a fairly large window size or it gets truncated.
- About, Preferences etc are normally linked from the appmenu
- preferences widget could be embedded in a gtk popover and linked to a button (three lines or cog), although in that case it would probably be better to have the toggle activate setting, rather than having apply/cancel buttons.
Since you guys probably don't use GNOME. This image shows a pretty good indication of what a native GNOME app would look like.
Splitting up the current toolbar into view switcher/search for example may be a bit too much work (not really looked throughly at your code)
But some of the other things, adding application menu, icons from GNOME symbolic icon set etc, should be fairly easy to implement.
It would probably be worth having a quick look at the GNOME HIG guide, where this image was taken from. Its available in gnome-devel-docs (3.14 only) or https:/