Best resolution for only secondary screen

src/lib.rs

@@ -143,22 +143,9 @@ impl Screen {
 
     /// Finds the best common resolution between two screens.
     fn best_common_resolution(&self, other: &Screen) -> Option<(u32, u32)> {
-
         let self_res: HashSet<(u32, u32)> = self.resolutions.clone().into_iter().collect();
         let other_res: HashSet<(u32, u32)> = other.resolutions.clone().into_iter().collect();
-        let intersection = self_res.intersection(&other_res);
-
-        let mut output = None;
-
-        for element in intersection {
-            match output {
-                None                         => output = Some(*element),
-                Some(res) if &res < element  => output = Some(*element),
-                _ => (),
-            }
-        }
-
-        output
+        self_res.intersection(&other_res).into_iter().max().cloned()
     }
 }
 
@@ -311,18 +298,26 @@ impl MultiScreen {
 
     /// Returns the arguments for enabling only the second screen.
     pub fn only_secondary_args(&self) -> Option<Vec<String>> {
-        if let Some((ref main, ref second)) = self.main_screens() {
+
+        let (main, second) = match self.main_screens() {
+            Some(x) => x,
+            None => return None,
+        };
+
+        let (width, height) = match second.resolutions.iter().max() {
+            Some(x) => x,
+            None => return None,
+        };
+
         Some(vec![
              "--output".to_owned(),
              main.name.clone(),
              "--off".to_owned(),
              "--output".to_owned(),
              second.name.clone(),
-                "--auto".to_owned(),
+             "--mode".to_owned(),
+             format!("{}x{}", width, height),
         ])
-        } else {
-            None
-        }
     }
 
     /// Calls the xrandr program to disable all screens except the primary.