Workaround for hovering pens and touch rejection

Some browsers do not send a pointer event to indicate that a hovering
pen has left the hovering range. This results in the pen still being
active, even if there are touch events and the pen is lifted. In this
case we manually remove the pen to prevent touch rejection.

src/input/uinput_device.rs

@@ -1,6 +1,7 @@
 use std::cmp::Ordering;
 use std::ffi::CString;
 use std::os::raw::{c_char, c_int};
+use std::time::{Duration, Instant};
 
 use crate::capturable::x11::X11Context;
 use crate::capturable::{Capturable, Geometry};
@@ -35,6 +36,7 @@ pub struct UInputDevice {
     touches: [Option<MultiTouch>; 5],
     tool_pen_active: bool,
     pen_touching: bool,
+    last_pen_event: Instant,
     capturable: Box<dyn Capturable>,
     geometry: Rect,
     name_mouse_device: String,
@@ -99,6 +101,7 @@ impl UInputDevice {
             touches: Default::default(),
             tool_pen_active: false,
             pen_touching: false,
+            last_pen_event: Instant::now(),
             capturable,
             geometry: Rect::default(),
             name_mouse_device: name_mouse,
@@ -304,6 +307,28 @@ impl InputDevice for UInputDevice {
                     }
                     self.num_touch_mapping_tries += 1;
                 }
+
+                // This is a workaround for browsers that send events when the pen is hovering but
+                // do not send an event when the pen leaves the hovering range. If the pen is left
+                // in this state touch rejection may stay active and touch won't work.
+                // Therefore, we manually remove the pen after a short delay.
+                if self.tool_pen_active
+                    && !self.pen_touching
+                    && (Instant::now() - self.last_pen_event) > Duration::from_millis(50)
+                {
+                    self.tool_pen_active = false;
+                    self.send(self.stylus_fd, ET_KEY, EC_KEY_TOUCH, 0);
+                    self.send(self.stylus_fd, ET_KEY, EC_KEY_TOOL_PEN, 0);
+                    self.send(self.stylus_fd, ET_KEY, EC_KEY_TOOL_RUBBER, 0);
+                    self.send(self.stylus_fd, ET_ABSOLUTE, EC_ABSOLUTE_PRESSURE, 0);
+                    self.send(
+                        self.stylus_fd,
+                        ET_MSC,
+                        EC_MSC_TIMESTAMP,
+                        (event.timestamp % (i32::MAX as u64 + 1)) as i32,
+                    );
+                    self.send(self.stylus_fd, ET_SYNC, EC_SYNC_REPORT, 0);
+                }
                 match event.event_type {
                     PointerEventType::DOWN
                     | PointerEventType::MOVE
@@ -446,6 +471,7 @@ impl InputDevice for UInputDevice {
                 };
             }
             PointerType::Pen => {
+                self.last_pen_event = Instant::now();
                 if self.num_stylus_mapping_tries < MAX_SCREEN_MAPPING_TRIES {
                     if let Some(x11ctx) = &mut self.x11ctx {
                         // Mapping input does not work on XWayland as xinput list does not expose