FS dock: Allow deselecting items by clicking empty space

Fixes #27546.

(cherry picked from commit 3da2894d82dd192cce483817aa0433c509a18c4d)

editor/filesystem_dock.cpp

@@ -2093,6 +2093,10 @@ void FileSystemDock::_tree_rmb_select(const Vector2 &p_pos) {
 	}
 }
 
+void FileSystemDock::_tree_empty_selected() {
+	tree->deselect_all();
+}
+
 void FileSystemDock::_file_list_rmb_select(int p_item, const Vector2 &p_pos) {
 	// Right click is pressed in the file list
 	Vector<String> paths;
@@ -2271,9 +2275,10 @@ void FileSystemDock::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("_toggle_split_mode"), &FileSystemDock::_toggle_split_mode);
 
 	ClassDB::bind_method(D_METHOD("_tree_rmb_option", "option"), &FileSystemDock::_tree_rmb_option);
-	ClassDB::bind_method(D_METHOD("_file_list_rmb_option", "option"), &FileSystemDock::_file_list_rmb_option);
-
 	ClassDB::bind_method(D_METHOD("_tree_rmb_select"), &FileSystemDock::_tree_rmb_select);
+	ClassDB::bind_method(D_METHOD("_tree_empty_selected"), &FileSystemDock::_tree_empty_selected);
+
+	ClassDB::bind_method(D_METHOD("_file_list_rmb_option", "option"), &FileSystemDock::_file_list_rmb_option);
 	ClassDB::bind_method(D_METHOD("_file_list_rmb_select"), &FileSystemDock::_file_list_rmb_select);
 	ClassDB::bind_method(D_METHOD("_file_list_rmb_pressed"), &FileSystemDock::_file_list_rmb_pressed);
 
@@ -2406,6 +2411,7 @@ FileSystemDock::FileSystemDock(EditorNode *p_editor) {
 	tree->connect("item_activated", this, "_tree_activate_file");
 	tree->connect("multi_selected", this, "_tree_multi_selected");
 	tree->connect("item_rmb_selected", this, "_tree_rmb_select");
+	tree->connect("nothing_selected", this, "_tree_empty_selected");
 	tree->connect("gui_input", this, "_tree_gui_input");
 
 	file_list_vb = memnew(VBoxContainer);

editor/filesystem_dock.h

@@ -237,6 +237,7 @@ private:
 	void _tree_rmb_select(const Vector2 &p_pos);
 	void _file_list_rmb_select(int p_item, const Vector2 &p_pos);
 	void _file_list_rmb_pressed(const Vector2 &p_pos);
+	void _tree_empty_selected();
 
 	struct FileInfo {
 		String name;