An Alt+Tab window switcher built around a rotating Earth, drawn from NASA satellite imagery and lit by the real position of the sun.
Your open windows ride on a ring around the globe's equator, each one shown as a live picture of what is inside it. Each Tab rolls the globe one step, so the next window comes round to the front and the rest travel with it. A few windows sit together as a band across the equator; it takes something like twenty before the ring closes and they wrap right around the world, with the far side passing behind the Earth.
The daylight on the globe is the daylight happening right now, and the view is turned to your own longitude, so you can see whether your part of the world is still in it.
It is a plain X11 program, not a desktop extension. Nothing is plugged into GNOME Shell, so there is nothing to break when GNOME updates, and it works the same on Xfce, KDE on X11, i3 or a bare window manager.
| Key | Action |
|---|---|
Alt+Tab |
open the switcher and roll the next window to the front |
Shift+Alt+Tab |
open backwards, roll the other way |
→ ↓ / ← ↑ |
keep rolling while it is open (keypad arrows too) |
Home / End |
jump to the first or last window |
release Alt, Enter or Space |
activate the window at the front |
Escape |
close without switching |
w, q or F4 |
close the window at the front |
| click a window | activate it |
| middle-click a window | close it |
| scroll wheel | keep rolling |
| click the backdrop | close without switching |
Windows are offered in most-recently-used order, so a single Alt+Tab flips between the last two windows, the way every other switcher behaves.
A globe sits in the system tray. Its menu opens a settings window whose Switcher tab carries the tuning that used to mean editing constants: globe size, window size, ring width and height, camera tilt, the spacing between windows, roll time, how far the desktop is dimmed, and how much daylight is left in the night side. Each slider says what moving it does. There are also switches for whether other workspaces are included and whether the window title is shown, and a button to put everything back.
Settings are saved as you move them, and apply the next time you press Alt+Tab.
- An X11 session. Wayland gives no way to list or raise other windows, so there is nothing this program could do there
- The Flutter SDK to build it, with the usual Linux desktop toolchain
- A window manager that supports EWMH, which in practice means all of them
On Debian/Ubuntu:
sudo apt install cmake ninja-build clang libgtk-3-dev \
libayatana-appindicator3-devgit clone https://github.com/maxbrito500/globeswitcher.git
cd globeswitcher
./install.shThe installer builds the app, copies it to ~/.local/share/globeswitcher/app,
starts it, and adds it to ~/.config/autostart so it comes back on login.
X11 only lets one program grab a given key, so whatever your desktop has bound to Alt+Tab has to let go of it first. On GNOME the installer does that for you and saves the old value; on other desktops, clear Alt+Tab in your keyboard settings yourself.
Every start, exit and crash is written to
~/.local/share/globeswitcher/globeswitcher.log, along with whatever the app
printed before it went. Look there first:
tail -50 ~/.local/share/globeswitcher/globeswitcher.log./uninstall.shThis stops the app, restores the Alt+Tab binding it took, and deletes everything it installed.
The map. Two equirectangular NASA images ship with the app: Blue Marble for daylight and Black Marble for city lights.
The globe. flutter_app/shaders/globe.frag does the projection and the
lighting together. For each pixel of the disc it works out the surface normal,
turns that into a latitude and longitude, looks both maps up, and mixes them by
the solar elevation at that same point — computed from the subsolar position,
which comes from the clock alone and no network service. The terminator is
therefore exact on every frame, with nothing to regenerate and nothing that can
go stale. A little daylight is left in the night side, because city lights
alone are close enough to black that half the globe would disappear.
The windows. Window i is pinned to a longitude on the equator, and its
place on screen is that point projected through the same camera the globe is
drawn with, lifted about 24° above the equator so the ring is a shallow band
around the waist rather than an arc over the poles. The ring also floats above
the equatorial plane: one lying exactly on it projects far below the globe's
centre, because the camera tilt multiplies the offset by the ring's radius
rather than the globe's, and the windows end up sweeping past the south pole.
The spacing is a fixed angle rather than 360°/n. Dividing the circle would
fling four windows out to the four cardinal points and leave the globe ringed
by empty space; a fixed step keeps a handful of windows together in front of
you, and only closes the ring once there are enough to go the whole way round.
Which windows are hidden needs no test. The far half is drawn first, then the globe, then the near half; because the globe is opaque inside its disc, a window crossing the limb is cut exactly at the silhouette.
Rolling. The selected window is whichever one faces you, so selection and rotation are the same thing: Tab picks the next window and sets the globe's target angle to that window's longitude, and the globe eases there, always taking the shorter way round. A Tab pressed mid-roll retargets from wherever the globe currently is, so drumming on Tab stays smooth. Wrapping from the last window back to the first travels the whole band, so that roll is given proportionally longer and reads as a turn rather than a jump.
The window list. Read from the X server through EWMH: _NET_CLIENT_LIST
for the windows, _NET_WM_ICON for the icons, _NET_WM_NAME for the titles,
XGetImage for the pictures, and a _NET_ACTIVE_WINDOW message to raise the
one you chose. X has no most-recently-used list, so the app keeps its own by
watching which window the window manager makes active.
All of that is dart:ffi straight against libX11 — no C plugin — and it sits
behind one WindowBackend interface. That is the part Flutter does not carry
across: listing another application's windows, picturing them, raising one and
taking over Alt+Tab have no Flutter API and differ on every desktop. Adding
Windows or macOS means writing one more implementation of that interface and
nothing else; the same dart:ffi approach would work against user32.dll.
One window, two hats. Flutter desktop gives an application a single window, so the same one is reconfigured rather than duplicated: undecorated, fullscreen and above everything as the switcher; an ordinary titled window as the settings panel; hidden the rest of the time.
globeswitcher/ and tools/ hold the first implementation, in Python with
numpy compositing on the CPU. It still works, and ./install-python.sh installs
it instead. Only one of the two can run at a time, because only one X client can
hold the Alt+Tab grab.
It is worth keeping as the reference the port was made from, and as the way to
run this on a machine without the Flutter SDK. It has no tray icon and no
settings panel; its tuning lives in constants at the top of
globeswitcher/ui.py, globeswitcher/globe.py and tools/globe-texture.
- X11 only. Wayland has no protocol for listing or activating another application's windows, short of a compositor-specific extension.
- The switcher covers the whole X screen rather than one monitor.
- Thumbnails of windows buried behind others depend on a compositing window manager keeping their contents. Without a compositor an obscured window has nothing to capture, and it falls back to its application icon.
- The tray menu is the way in to settings: under GNOME's AppIndicator support a left click opens that menu rather than firing an activate event.
- Past about twenty windows the ring closes and the tiles start to overlap near the limbs, where the spacing foreshortens.
Satellite imagery courtesy of NASA Visible Earth: Blue Marble: Next Generation and Black Marble. NASA imagery is in the public domain.
Apache License 2.0 — see LICENSE.