wezterm: add tab_max_width config option

This allows setting the maximum width of a tab in the tab tab.
It defaults to 16 glyphs in width.

refs: https://github.com/wez/wezterm/issues/255

docs/changelog.markdown

@@ -25,6 +25,9 @@ brief notes about them may accumulate here.
   client-side window decoration so let's just make it opt-in so
   that the default experience is better.
 * Fixed a crash on Linux/X11 when using `wezterm connect HOST`
+* Added `tab_max_width` config setting to limit the maximum
+  width of tabs in the tab tab.  This defaults to 16 glyphs
+  in width.
 
 ### 20200718-095447-d2315640
 

docs/config/misc.markdown

@@ -65,7 +65,10 @@ return {
   -- `SteadyUnderline`, `BlinkingUnderline`, `SteadyBar`,
   -- and `BlinkingBar`.
   default_cursor_style = "SteadyBlock",
+
+  -- Specifies the maximum width that a tab can have in the
+  -- tab bar.  Defaults to 16 glyphs in width.
+  tab_max_width = 16,
 }
 ```
 
-

src/config/mod.rs

@@ -461,6 +461,11 @@ pub struct Config {
     #[serde(default = "default_true")]
     pub enable_tab_bar: bool,
 
+    /// Specifies the maximum width that a tab can have in the
+    /// tab bar.  Defaults to 16 glyphs in width.
+    #[serde(default = "default_tab_max_width")]
+    pub tab_max_width: usize,
+
     /// If true, hide the tab bar if the window only has a single tab.
     #[serde(default)]
     pub hide_tab_bar_if_only_one_tab: bool,
@@ -539,6 +544,10 @@ pub struct Config {
     pub enable_csi_u_key_encoding: bool,
 }
 
+fn default_tab_max_width() -> usize {
+    16
+}
+
 fn default_update_interval() -> u64 {
     86400
 }

src/frontend/gui/tabbar.rs

@@ -48,6 +48,7 @@ impl TabBarState {
         mouse_x: Option<usize>,
         window: &Ref<MuxWindow>,
         colors: Option<&TabBarColors>,
+        tab_width_max: usize,
     ) -> Self {
         // We ultimately want to produce a line looking like this:
         // ` | tab1-title x | tab2-title x |  +      . - X `
@@ -82,7 +83,8 @@ impl TabBarState {
         } else {
             // We need to clamp the length to balance them out
             available_cells / number_of_tabs
-        };
+        }
+        .min(tab_width_max);
 
         let colors = colors.cloned().unwrap_or_else(TabBarColors::default);
 

src/frontend/gui/termwindow.rs

@@ -1139,6 +1139,7 @@ impl TermWindow {
             },
             &window,
             config.colors.as_ref().and_then(|c| c.tab_bar.as_ref()),
+            config.tab_max_width,
         );
         if new_tab_bar != self.tab_bar {
             self.tab_bar = new_tab_bar;