hop

A configurable X11 Alt+Tab window switcher written in Rust, with ARGB transparency, live window thumbnails, and compositor blur support.

Features

• Live thumbnails — each tile can show a real screenshot of the window (via the compositor's backing pixmap), or the app icon, per config
• App icons from _NET_WM_ICON, with an XDG icon-theme fallback by WM_CLASS
• Window title labels rendered with Xft (antialiased, Fontconfig fonts)
• ARGB 32-bit transparency — semi-transparent tile and popup backgrounds
• Compositor blur via the _KDE_NET_WM_BLUR_BEHIND_REGION hint (whole popup or per-tile) — honored by picom, KWin, and other compositors
• Styling — rounded corners, configurable borders, gradients, drop shadows
• Type-to-filter — start typing while the popup is open to narrow the list by window title or WM_CLASS (case-insensitive); Backspace deletes, and the grid resizes to fit. Keystrokes that would match nothing are ignored.
• Quick-select — number badges (1–9) on the first nine tiles; press a digit to jump straight to that window (toggle with window.quick_select)
• Same-app cycling — a second binding (default Super+Tab) opens the popup filtered to just the windows of the currently-active app (same WM_CLASS)
• Close windows — the close key (default Delete) or a middle-click on a tile closes that window via _NET_CLOSE_WINDOW without leaving the switcher
• Navigation — Tab/Shift+Tab to cycle, or arrow keys to move across the grid
• Mouse support — hover to select, click to activate, scroll to cycle
• Multi-monitor — the popup centers on the monitor under the pointer
• Configurable keybindings — modifier, next, prev, cancel, and close keys via TOML
• Fast — the popup paints immediately; icons and thumbnails stream in progressively without blocking input
• Pure-Rust X11 via x11rb (Xft text is the only C dependency)

Requirements

• An X11 session with EWMH support (tested on XFCE / xfwm4)
• A compositor for transparency and blur. picom is recommended; live thumbnails require a compositor with the COMPOSITE extension (without one, tiles fall back to icons)
• Build-time: a Rust toolchain and the X11 + Xft development libraries (e.g. on Arch: libx11, libxft, libxrender, which are usually already present in a desktop install)

Building

cargo build --release

The binary ends up at target/release/hop.

Installing

install -Dm755 target/release/hop ~/.local/bin/hop

Configuration

hop reads $XDG_CONFIG_HOME/hop/config.toml (defaults to ~/.config/hop/config.toml). If no config is found, built-in Dracula-themed defaults are used. Edits take effect the next time the popup opens — no restart needed.

mkdir -p ~/.config/hop
cp config.example.toml ~/.config/hop/config.toml

config.example.toml documents every option. A taste:

[window]
position           = "center"     # "center" or "x,y"
background         = "#282a36ff"   # popup background (gap/border areas)
border_radius      = 0             # popup corner radius (px)
blur               = false         # blur behind the whole popup

[tile]
width        = 200
height       = 150
content      = "icon"             # "icon" or "thumbnail"
icon_overlay = true               # small corner icon over thumbnails
background   = "#282a36cc"
frame        = "#bd93f9ff"         # selected tile border
inactive     = "#44475aff"         # unselected tile border

[font]
name = "Roboto"
size = 11

[keys]
modifier = "Alt"
next     = "Tab"
prev     = "Shift+Tab"
cancel   = "Escape"

Colors accept #rrggbb (opaque) or #rrggbbaa (with alpha).

Autostart (XFCE)

Create ~/.config/autostart/hop.desktop:

[Desktop Entry]
Type=Application
Name=hop
Exec=/home/<user>/.local/bin/hop
Hidden=false
X-XFCE-Autostart-Override=true

Disable xfwm4's built-in Alt+Tab so it doesn't conflict:

xfconf-query -c xfwm4 -p /general/cycle_windows_key -s ""

Compositor setup

hop draws with an ARGB visual and asks the compositor to blur behind the popup by setting the standard _KDE_NET_WM_BLUR_BEHIND_REGION hint (honored by picom, KWin, and others). hop never edits your compositor's config — it only sets the hint and its own WM_CLASS = "hop", so you stay in control of your compositor and hop works with whatever you run. You enable blur (and any shadow/corner rules) yourself, once.

picom

Run picom for transparency, blur, and live thumbnails. To enable blur globally:

blur-background = true;
blur-method = "dual_kawase";
blur-strength = 8;

hop's popup is matchable as class_g = 'hop'. Use that to tune picom's effects for the switcher — for example, to keep blur but drop the shadow and rounded corners on the popup:

shadow-exclude = [ "class_g = 'hop'" ];
rounded-corners-exclude = [ "class_g = 'hop'" ];

Other compositors

Any compositor that honors _KDE_NET_WM_BLUR_BEHIND_REGION (e.g. KWin) will blur behind the popup with no extra setup. Compositors that don't support the hint still render hop's ARGB transparency; you just won't get blur. Live thumbnails require a compositor with the COMPOSITE extension.