Window Snapper

A GNOME Shell extension that adds 12 snap zones to your Ubuntu desktop — drag any window to a screen edge to snap it to thirds, halves, or quarters.

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Snap zones

┌──────────────────────────────────────────────────────────────┐
│  [↖ top-left ¼]    [▲ center column ⅓ ]    [↗ top-right ¼] │  ← TOP edge
├──┬───────────────────────────────────────────────────────┬───┤
│⅓ │                                                       │ ⅓ │  ← cursor top third
│  │                                                       │   │
├──┤                                                       ├───┤
│½ │                   drag a window here                  │ ½ │  ← cursor middle third
│  │                                                       │   │
├──┤                                                       ├───┤
│⅔ │                                                       │ ⅔ │  ← cursor bottom third
│  │                                                       │   │
├──┴───────────────────────────────────────────────────────┴───┤
│  [↙ bot-left ¼]    [▼ bottom ½ — full width]  [↘ bot-right ¼│  ← BOTTOM edge
└──────────────────────────────────────────────────────────────┘
  ↑ LEFT edge                                    RIGHT edge ↑

Left edge — drag cursor to left side, release at vertical position:

Cursor position	Result
Top third of screen	Left ⅓ (33% width, full height)
Middle third	Left ½ (50% width, full height)
Bottom third	Left ⅔ (66% width, full height)

Right edge — mirror of left:

Cursor position	Result
Top third	Right ⅓
Middle third	Right ½
Bottom third	Right ⅔

Top edge — drag cursor to top, release at horizontal position:

Cursor position	Result
Left third	Top-left quarter (50% × 50%)
Center third	Center column (⅓ width, full height)
Right third	Top-right quarter (50% × 50%)

Bottom edge:

Cursor position	Result
Left third	Bottom-left quarter
Center third	Bottom half (full width)
Right third	Bottom-right quarter

Note — intentional asymmetry: top-center is a ⅓-wide center column (full height), while bottom-center is a bottom half (full width). The two behaviours complement each other rather than mirroring, giving access to both a centered narrow column and a wide horizontal pane without using a modifier.

Hold Shift — 2×3 grid mode

Hold Shift during the drag to switch to a 6-cell grid. The edge panels turn gold to indicate grid mode is active.

Edge	Cursor position	Result
Top	Left third	Cell 1 — top-left ⅓×½
Top	Center third	Cell 2 — top-center ⅓×½
Top	Right third	Cell 3 — top-right ⅓×½
Bottom	Left third	Cell 4 — bottom-left ⅓×½
Bottom	Center third	Cell 5 — bottom-center ⅓×½
Bottom	Right third	Cell 6 — bottom-right ⅓×½

Release Shift at any time to return to normal mode.

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Requirements

• Ubuntu (or any distro running GNOME Shell)
• GNOME Shell 45 or newer (ESM extension format)
  • Ubuntu 23.10 → GNOME 45
  • Ubuntu 24.04 → GNOME 46
  • Ubuntu 25.04 → GNOME 48

Check your version:

gnome-shell --version

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Installation

cd ~/window-snapper
bash install.sh

The script will:

1. Detect your GNOME Shell version and pick the right extension format
2. Copy the files to ~/.local/share/gnome-shell/extensions/window-snapper@local/
3. Enable the extension

Restart GNOME Shell to activate

X11 (no logout needed):

Press Alt + F2, type r, press Enter

Wayland:

Log out and log back in

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Usage

1. Click and hold any window's title bar to start dragging
2. Indicator panels appear on all four screen edges showing available snap zones
3. Drag toward an edge — a blue preview overlay highlights where the window will land
4. Release the mouse — the window snaps into place

The vertical position on left/right edges controls the width. The horizontal position on top/bottom edges controls the height.

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Snapping 3 windows side by side

To fill the screen with 3 equal columns:

1. Drag window A → left edge, top third → snaps to left ⅓
2. Drag window B → right edge, top third → snaps to right ⅓
3. Drag window C → top edge, center third → snaps to center ⅓

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Preferences

Open the preferences dialog with:

gnome-extensions prefs window-snapper@local

Configurable knobs:

Setting	Default	Description
Left/right edge width	60 px	How close to a side edge a drag must be before a zone activates
Top/bottom edge height	30 px	How close to the top/bottom edge a drag must be before a zone activates
Snap delay after drop	50 ms	Pause between releasing the mouse and resizing the window
Enable 2×3 grid mode with Shift	on	Turn off if Shift+drag conflicts with another action

Changes apply immediately to the next drag — no restart required.

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Uninstall

gnome-extensions disable window-snapper@local
rm -rf ~/.local/share/gnome-shell/extensions/window-snapper@local

Then restart GNOME Shell (see above).

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Troubleshooting

Extension doesn't appear after install

Make sure you restarted GNOME Shell. On Wayland this requires a full log out/in.

Windows don't snap

Some windows (dialogs, system windows) have fixed sizes and can't be resized by extensions.

Snap zones not showing up during drag

Verify the extension is enabled: gnome-extensions list --enabled | grep window-snapper

Re-run install after a GNOME update

Major GNOME updates may require reinstalling: bash ~/window-snapper/install.sh