fix(linux): fullscreen on current monitor (#320)

.changes/fix-fullscreen-linux.md

@@ -0,0 +1,5 @@
+---
+"tao": patch
+---
+
+Fixes the `set_fullscreen` implementation on Linux when the `Fullscreen::Borderless` value is set to `None`.

examples/fullscreen.rs

@@ -16,7 +16,7 @@ fn main() {
   env_logger::init();
   let event_loop = EventLoop::new();
 
-  print!("Please choose the fullscreen mode: (1) exclusive, (2) borderless: ");
+  print!("Please choose the fullscreen mode: (1) exclusive, (2) borderless, (3) borderless on current monitor: ");
   stdout().flush().unwrap();
 
   let mut num = String::new();
@@ -26,6 +26,7 @@ fn main() {
   let fullscreen = Some(match num {
     1 => Fullscreen::Exclusive(prompt_for_video_mode(&prompt_for_monitor(&event_loop))),
     2 => Fullscreen::Borderless(Some(prompt_for_monitor(&event_loop))),
+    3 => Fullscreen::Borderless(None),
     _ => panic!("Please enter a valid number"),
   });
 

src/platform_impl/linux/event_loop.rs

@@ -259,10 +259,14 @@ impl<T: 'static> EventLoop<T> {
           }
           WindowRequest::Fullscreen(fullscreen) => match fullscreen {
             Some(f) => {
-              if let Fullscreen::Borderless(Some(monitor)) = f {
-                let number = monitor.inner.number;
-                let screen = window.display().default_screen();
-                window.fullscreen_on_monitor(&screen, number);
+              if let Fullscreen::Borderless(m) = f {
+                if let Some(monitor) = m {
+                  let number = monitor.inner.number;
+                  let screen = window.display().default_screen();
+                  window.fullscreen_on_monitor(&screen, number);
+                } else {
+                  window.fullscreen();
+                }
               }
             }
             None => window.unfullscreen(),