Troubleshooting

#Nothing happens when I slide or press

Windows: check that you have a precision touchpad (Settings → Bluetooth & devices → Touchpad says "Your PC has a precision touchpad"). Touchpads with an older, non-precision driver don't report finger positions to Windows, so Margin can't read them.
Make sure Margin is on (Windows: the tray menu shows On ticked) and the edge or corner is assigned (assigned zones are tinted on the map).
Windows: tray menu → Open log, or run margin.exe --diag from a terminal. Linux: margin --diag, or journalctl --user -u margin. They show whether Margin sees your finger and what it decides.

#Linux: "cannot read /dev/input/event…" or "cannot create the virtual keyboard"

Margin lacks the permissions described under Permissions. Run the installer again, or do the manual steps, then log out and back in. id should list the input group, and ls -l /dev/uinput should show group input with rw.

#Linux: keys are sent but nothing happens in some apps

Margin sends real key events through a virtual keyboard, so the app or desktop decides what they do. Brightness and volume use the media keys, so they work if your desktop reacts to those keys. Window and desktop switching depend on your desktop's own shortcuts; set the keys you want under Custom keys….

#Brightness says "not available" (Windows)

Brightness uses Windows' built-in display interface, which only exists for a laptop's own screen. External monitors and most desktop PCs don't have it.

#Slides start when I only meant to move the pointer

Make the edge smaller with the Edge size slider, switch to Press the edge until it clicks (Windows), or turn that edge off by setting it to Nothing.

#It doesn't work in one particular app (Windows)

Windows doesn't let a normal program send keys to an app that runs as administrator. Run Margin as administrator too, or use it with that app closed. Some players use different shortcuts for seeking, so try Custom keys for the bottom edge.

#The Record button won't capture Alt+Tab (or Win/Super combos)

The system handles those combinations before any program sees them. Type the text into the box instead, for example Alt+Tab.

#Another touchpad utility reacts to the same edges

Some vendor touchpad tools (Synaptics, ELAN, Lenovo, ASUS and similar) have their own edge features. If both react, turn one of them off.

#The browser or SmartScreen warns about margin.exe

A new program that few people have downloaded yet gets this warning; nothing was found in it. Use the PowerShell installer from Download, or keep the file (Edge: Keep anyway; Chrome: Download anyway; SmartScreen: More info → Run anyway).