Add a focus-tab remote command

Fixes #394

kitty/boss.py

@@ -124,7 +124,10 @@ class Boss:
             }
 
     def match_windows(self, match):
+        try:
             field, exp = match.split(':', 1)
+        except ValueError:
+            return
         pat = re.compile(exp)
         for tm in self.os_window_map.values():
             for tab in tm:
@@ -140,7 +143,10 @@ class Boss:
                         return tab
 
     def match_tabs(self, match):
+        try:
             field, exp = match.split(':', 1)
+        except ValueError:
+            return
         pat = re.compile(exp)
         tms = tuple(self.os_window_map.values())
         found = False
@@ -516,6 +522,11 @@ class Boss:
         if tm is not None:
             tm.goto_tab(tab_num - 1)
 
+    def set_active_tab(self, tab):
+        tm = self.active_tab_manager
+        if tm is not None:
+            tm.set_active_tab(tab)
+
     def next_tab(self):
         tm = self.active_tab_manager
         if tm is not None:

kitty/remote_control.py

@@ -401,6 +401,27 @@ def focus_window(boss, window, payload):
 # }}}
 
 
+# focus_tab {{{
+@cmd(
+    'Focus the specified tab',
+    'The active window in the specified tab will be focused.',
+    options_spec=MATCH_TAB_OPTION,
+    argspec='',
+)
+def cmd_focus_tab(global_opts, opts, args):
+    return {'match': opts.match}
+
+
+def focus_tab(boss, window, payload):
+    match = payload['match']
+    tabs = tuple(boss.match_tabs(match))
+    if not tabs:
+        raise MatchError(match, 'tabs')
+    tab = tabs[0]
+    boss.set_active_tab(tab)
+# }}}
+
+
 # get_text {{{
 @cmd(
     'Get text from the specified window',

remote-control.asciidoc

@@ -57,9 +57,14 @@ Let's change the title of the current tab:
 
    kitty @ set-tab-title Master Tab
 
-Now lets switch to the newly opened tab.
+Now lets switch to the newly opened tab:
 
-   kitty @ focus-window --match title:New
+   kitty @ focus-tab --match title:New
+
+Similarly, to focus the previously opened output window (which will also switch
+back to the old tab, automatically):
+
+   kitty @ focus-window --match title:Output
 
 You can get a listing of available tabs and windows, by running: