FileManager: Make DirectoryView listen for configuration changes

DirectoryView now inherits from Config::Listener and will update its
view mode immediately if changed from elsewhere.

This is pretty neat. :^)

Userland/Applications/FileManager/DirectoryView.cpp

@@ -340,6 +340,17 @@ void DirectoryView::set_view_mode_from_string(String const& mode)
     }
 }
 
+void DirectoryView::config_string_did_change(String const& domain, String const& group, String const& key, String const& value)
+{
+    if (domain != "FileManager" || group != "DirectoryView")
+        return;
+
+    if (key == "ViewMode") {
+        set_view_mode_from_string(value);
+        return;
+    }
+}
+
 void DirectoryView::set_view_mode(ViewMode mode)
 {
     if (m_view_mode == mode)

Userland/Applications/FileManager/DirectoryView.h

@@ -8,6 +8,7 @@
 
 #include <AK/URL.h>
 #include <AK/Vector.h>
+#include <LibConfig/Listener.h>
 #include <LibDesktop/Launcher.h>
 #include <LibGUI/Action.h>
 #include <LibGUI/ColumnsView.h>
@@ -38,7 +39,8 @@ private:
 
 class DirectoryView final
     : public GUI::StackWidget
-    , private GUI::ModelClient {
+    , private GUI::ModelClient
+    , public Config::Listener {
     C_OBJECT(DirectoryView);
 
 public:
@@ -130,6 +132,9 @@ public:
     GUI::Action& view_as_table_action() { return *m_view_as_table_action; }
     GUI::Action& view_as_columns_action() { return *m_view_as_columns_action; }
 
+    // ^Config::Listener
+    virtual void config_string_did_change(String const& domain, String const& group, String const& key, String const& value) override;
+
 private:
     explicit DirectoryView(Mode);
 

Userland/Applications/FileManager/main.cpp

@@ -92,6 +92,7 @@ int main(int argc, char** argv)
     }
 
     Config::pledge_domains({ "FileManager", "WindowManager" });
+    Config::monitor_domain("FileManager");
 
     if (is_desktop_mode)
         return run_in_desktop_mode();