Fix linux zeta modifiers display (#24764)

Improves rendering of Zeta keybind shortcuts on Linux

Before:

![image](https://github.com/user-attachments/assets/9b6a61f7-dade-480f-a864-acdcede05957)

After: (with muting modifier changes merged)

![image](https://github.com/user-attachments/assets/dd616d29-ac2e-4c8b-bf9b-5d74f8e4f1c4)


Release Notes:

- N/A

---------

Co-authored-by: Michael <michael@zed.dev>
Co-authored-by: Agus <agus@zed.dev>

crates/ui/src/components/keybinding.rs

@@ -92,7 +92,7 @@ impl RenderOnce for KeyBinding {
                         self.platform_style,
                         None,
                         self.size,
-                        false,
+                        true,
                     ))
                     .map(|el| {
                         el.child(render_key(&keystroke, self.platform_style, None, self.size))
@@ -110,7 +110,7 @@ pub fn render_key(
     let key_icon = icon_for_key(keystroke, platform_style);
     match key_icon {
         Some(icon) => KeyIcon::new(icon, color).size(size).into_any_element(),
-        None => Key::new(capitalize(&keystroke.key), color)
+        None => Key::new(util::capitalize(&keystroke.key), color)
             .size(size)
             .into_any_element(),
     }
@@ -145,10 +145,12 @@ pub fn render_modifiers(
     platform_style: PlatformStyle,
     color: Option<Color>,
     size: Option<AbsoluteLength>,
-    standalone: bool,
+    trailing_separator: bool,
 ) -> impl Iterator<Item = AnyElement> {
+    #[derive(Clone)]
     enum KeyOrIcon {
         Key(&'static str),
+        Plus,
         Icon(IconName),
     }
 
@@ -200,23 +202,34 @@ pub fn render_modifiers(
         .into_iter()
         .filter(|modifier| modifier.enabled)
         .collect::<Vec<_>>();
-    let last_ix = filtered.len().saturating_sub(1);
 
-    filtered
+    let platform_keys = filtered
         .into_iter()
-        .enumerate()
-        .flat_map(move |(ix, modifier)| match platform_style {
-            PlatformStyle::Mac => vec![modifier.mac],
-            PlatformStyle::Linux if standalone && ix == last_ix => vec![modifier.linux],
-            PlatformStyle::Linux => vec![modifier.linux, KeyOrIcon::Key("+")],
-            PlatformStyle::Windows if standalone && ix == last_ix => {
-                vec![modifier.windows]
-            }
-            PlatformStyle::Windows => vec![modifier.windows, KeyOrIcon::Key("+")],
+        .map(move |modifier| match platform_style {
+            PlatformStyle::Mac => Some(modifier.mac),
+            PlatformStyle::Linux => Some(modifier.linux),
+            PlatformStyle::Windows => Some(modifier.windows),
+        });
+
+    let separator = match platform_style {
+        PlatformStyle::Mac => None,
+        PlatformStyle::Linux => Some(KeyOrIcon::Plus),
+        PlatformStyle::Windows => Some(KeyOrIcon::Plus),
+    };
+
+    let platform_keys = itertools::intersperse(platform_keys, separator.clone());
+
+    platform_keys
+        .chain(if modifiers.modified() && trailing_separator {
+            Some(separator)
+        } else {
+            None
         })
+        .flatten()
         .map(move |key_or_icon| match key_or_icon {
             KeyOrIcon::Key(key) => Key::new(key, color).size(size).into_any_element(),
             KeyOrIcon::Icon(icon) => KeyIcon::new(icon, color).size(size).into_any_element(),
+            KeyOrIcon::Plus => "+".into_any_element(),
         })
 }
 
@@ -389,7 +402,7 @@ pub fn text_for_keystroke(keystroke: &Keystroke, platform_style: PlatformStyle)
     let key = match keystroke.key.as_str() {
         "pageup" => "PageUp",
         "pagedown" => "PageDown",
-        key => &capitalize(key),
+        key => &util::capitalize(key),
     };
 
     text.push_str(key);
@@ -397,14 +410,6 @@ pub fn text_for_keystroke(keystroke: &Keystroke, platform_style: PlatformStyle)
     text
 }
 
-fn capitalize(str: &str) -> String {
-    let mut chars = str.chars();
-    match chars.next() {
-        None => String::new(),
-        Some(first_char) => first_char.to_uppercase().collect::<String>() + chars.as_str(),
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;