Module role 

What kind of window a WindowDesc asks for: an application window, a panel, or a popup.

Most programs want WindowRole::Toplevel, the window every desktop has. The other two are for desktop furniture — a status bar, a launcher, a notification, a menu opened from a bar — which every window system has a different mechanism for, and which no program should have to write three times:

role	Wayland	Win32	AppKit
Panel	zwlr_layer_surface_v1	a topmost tool window; an appbar when it reserves an edge	a non-activating NSPanel
Popup	xdg_popup	a WS_POPUP tool window	a child NSPanel

Which roles a backend can build is in its caps — ShellCaps::PANEL and ShellCaps::POPUP — and asking for one it cannot is ShellError::Unsupported, never a toplevel in its place: a bar that silently became a normal window would cover the desktop it was meant to sit at the edge of.

Structs

Margins

Space around a panel, in logical units.

PanelAnchor

The monitor edges a panel is held against.

PanelDesc

Where a panel goes and how it behaves.

PopupDesc

Where a popup goes.

Enums

PanelKeyboard

Whether a panel takes the keyboard.

PanelLayer

The band of the stack a panel lives in, bottom to top.

PopupInput

What input a popup takes.

PopupPlacement

Which side of its anchor a popup opens on.

Reserve

Whether a panel keeps other windows out of its space.

WindowRole

What kind of window to create — see the module docs.