Add tab indicator for working terminal tab

data/terminal.metainfo.xml.in

@@ -71,6 +71,7 @@
         </ul>
       </description>
       <issues>
+        <issue url="https://github.com/elementary/terminal/issues/317">Show symbol while terminal is working</issue>
         <issue url="https://github.com/elementary/terminal/issues/653">Links open when clicking on Terminal app in Alt+Tab</issue>
         <issue url="https://github.com/elementary/terminal/issues/643">Port Terminal to GTK4</issue>
         <issue url="https://github.com/elementary/terminal/issues/510">Natural Copy/Paste. Ctrl+c clears the highlighted word. Ctrl+x doesn't.</issue>

src/Application.vala

@@ -183,6 +183,8 @@ public class Terminal.Application : Gtk.Application {
 
             if (terminal != terminal.main_window.current_terminal) {
                 terminal.tab_state = tab_state;
+            } else if (terminal.tab_state == WORKING) {
+                terminal.tab_state = NONE;
             }
 
             if (!(get_active_window ().is_active)) {

src/MainWindow.vala

@@ -303,7 +303,9 @@ namespace Terminal {
                     return;
                 }
 
-                term.tab_state = NONE;
+                if (term.tab_state != WORKING) {
+                    term.tab_state = NONE;
+                }
             });
 
             notebook.tab_bar.bind_property ("tabs-revealed", new_tab_revealer, "reveal-child", SYNC_CREATE | INVERT_BOOLEAN);

src/Widgets/TerminalView.vala

@@ -171,6 +171,7 @@ public class Terminal.TerminalView : Granite.Bin {
 
         terminal_widget.notify["tab-state"].connect (() => {
             tab.icon = terminal_widget.tab_state.to_icon ();
+            tab.loading = terminal_widget.tab_state == WORKING;
         });
 
         //Set correct label now to avoid race when spawning shell

src/Widgets/TerminalWidget.vala

@@ -7,6 +7,7 @@ namespace Terminal {
     public class TerminalWidget : Vte.Terminal {
         public enum TabState {
             NONE,
+            WORKING,
             COMPLETED,
             ERROR;
 
@@ -242,6 +243,7 @@ namespace Terminal {
             notify["width-request"].connect (() => resized = true);
             contents_changed.connect (on_contents_changed);
             child_exited.connect (on_child_exited);
+            window_title_changed.connect (on_window_title_changed);
             ulong once = 0;
             once = realize.connect (() => {
                 clipboard = Gdk.Display.get_default ().get_clipboard ();
@@ -802,6 +804,14 @@ namespace Terminal {
             fg_pid = -1;
         }
 
+        private void on_window_title_changed () {
+            if (has_foreground_process ()) {
+                tab_state = WORKING;
+            }
+
+            // Application.dbus_register handles resetting the state
+        }
+
         public void kill_fg () {
             int fg_pid;
             if (this.try_get_foreground_pid (out fg_pid)) {