How do I move a frameless window in Electron without using -webkit-app-region

Since your windows are frameless you can use the property -webkit-app-region which is valid even though your IDE says it’s not. You just should forbid the text selection and drag on buttons inside of your title bar too out of UX concerns.

.titlebar {
  -webkit-user-select: none;
  -webkit-app-region: drag;
}

.titlebar-button {
  -webkit-app-region: no-drag;
}

The API documentation mentions this too https://github.com/electron/electron/blob/master/docs/api/frameless-window.md#draggable-region