LibGUI: Add modified bool to TabWidget

This will allow application with multiple tabs to track modifications
per-tab, not just if the entire window has been modified

Userland/Libraries/LibGUI/TabWidget.cpp

@@ -53,7 +53,7 @@ TabWidget::TabWidget()
 
 ErrorOr<void> TabWidget::try_add_widget(Widget& widget)
 {
-    m_tabs.append({ widget.title(), nullptr, &widget });
+    m_tabs.append({ widget.title(), nullptr, &widget, false });
     add_child(widget);
     update_focus_policy();
     if (on_tab_count_change)
@@ -603,6 +603,32 @@ void TabWidget::set_tab_icon(Widget& tab, Gfx::Bitmap const* icon)
     }
 }
 
+bool TabWidget::is_tab_modified(Widget& tab_input)
+{
+    auto it = m_tabs.find_if([&](auto t) { return t.widget == &tab_input; });
+    if (it.is_end())
+        return false;
+    auto& tab = *it;
+    return tab.modified;
+}
+
+void TabWidget::set_tab_modified(Widget& tab_input, bool modified)
+{
+    auto it = m_tabs.find_if([&](auto t) { return t.widget == &tab_input; });
+    if (it.is_end())
+        return;
+    auto& tab = *it;
+    if (tab.modified != modified) {
+        tab.modified = modified;
+        update();
+    }
+}
+
+bool TabWidget::is_any_tab_modified()
+{
+    return any_of(m_tabs, [](auto& t) { return t.modified; });
+}
+
 void TabWidget::activate_next_tab()
 {
     if (m_tabs.size() <= 1)

Userland/Libraries/LibGUI/TabWidget.h

@@ -79,6 +79,10 @@ public:
     void set_tab_title(Widget& tab, StringView title);
     void set_tab_icon(Widget& tab, Gfx::Bitmap const*);
 
+    bool is_tab_modified(Widget& tab);
+    void set_tab_modified(Widget& tab, bool modified);
+    bool is_any_tab_modified();
+
     void activate_next_tab();
     void activate_previous_tab();
     void activate_last_tab();
@@ -139,6 +143,7 @@ private:
         DeprecatedString title;
         RefPtr<Gfx::Bitmap> icon;
         Widget* widget { nullptr };
+        bool modified { false };
     };
     Vector<TabData> m_tabs;
     TabPosition m_tab_position { TabPosition::Top };