Server-side decorations

By default, Singularity apps decorate themselves. They draw their own controls as bubbles and ask the compositor not to add a titlebar. This is client-side decoration, or CSD, and it is what gives the desktop its clean, titlebar-free look.

You can change that. In the desktop settings, under window management, there is an option to disable client-side decorations. Turn it on and the compositor draws the titlebars instead, the server-side way.

What the compositor draws

When server-side decorations are on, labwc draws the titlebar around each window. The shell themes those titlebars to match the rest of the desktop, tinting them lightly with your accent color, so a server-drawn bar still looks like Singularity rather than a generic frame.

How apps react

Not every app responds the same way, because they ask for decorations differently.

Singularity apps drop their floating bubbles and fold the same buttons into an ordinary toolbar strip, letting the compositor draw the titlebar above it. Their rounded corners go square, since the server titlebar reaches the window edge.
GTK apps are told not to draw their own decorations, so they request a server titlebar, which labwc draws and themes.
Qt apps are nudged the same way through their Wayland environment, so they stop drawing their own mismatched titlebars and fall in line with the rest.

The aim is consistency: GTK, Qt, and Singularity apps all show titlebars that match the rest of the desktop.