message: Fix scroll percentage calculation in `Scrollable`
diff: @@ -415,7 +415,8 @@ impl Scrollbar {
  grabbed_at: f32,
  cursor_position: Point,
  ) -> f32 {
  - (cursor_position.y + self.bounds.y
  + (cursor_position.y
  + - self.bounds.y
  - self.scroller.bounds.height * grabbed_at)
  / (self.bounds.height - self.scroller.bounds.height)
  }
  