Some improvements to file/dir open/save dialogs:

1. Removed "..", instead you now will see "Select Current Folder" and "Select this Folder" buttons.
2. Added "go to parent folder" (^) button to Save a File dialog.
3. Tree.cpp: "nothing_selected" signal has been re-made (previous implementation, merged in #13308, wasn't optimal in context of performance)
4. Fixed issue in Project Export dialog: MODE_SAVE_FILE wasn't set when you click "Export".
5. Now you can deselect items by clicking on empty space in Open a Directory dialog.

6 files changed, 84 insertions, 15 deletions

diff --git a/editor/editor_file_dialog.cpp b/editor/editor_file_dialog.cpp
index c78b11737e..eb5af2eaeb 100644
--- a/editor/editor_file_dialog.cpp
+++ b/editor/editor_file_dialog.cpp
@@ -586,7 +586,7 @@ void EditorFileDialog::update_file_list() {
 
 	while ((item = dir_access->get_next(&isdir)) != "") {
 
-		if (item == ".")
+		if (item == "." || item == "..")
 			continue;
 
 		ishidden = dir_access->current_is_hidden();
@@ -599,11 +599,6 @@ void EditorFileDialog::update_file_list() {
 		}
 	}
 
-	if (dirs.find("..") == NULL) {
-		//may happen if lacking permissions
-		dirs.push_back("..");
-	}
-
 	dirs.sort_custom<NaturalNoCaseComparator>();
 	files.sort_custom<NaturalNoCaseComparator>();
 
diff --git a/editor/project_export.cpp b/editor/project_export.cpp
index 6500b10a3a..767dbcc27b 100644
--- a/editor/project_export.cpp
+++ b/editor/project_export.cpp
@@ -723,6 +723,7 @@ void ProjectExportDialog::_export_project() {
 		export_project->add_filter("*." + extension + " ; " + platform->get_name() + " Export");
 	}
 
+	export_project->set_mode(FileDialog::MODE_SAVE_FILE);
 	export_project->popup_centered_ratio();
 }
 
diff --git a/scene/gui/file_dialog.cpp b/scene/gui/file_dialog.cpp
index 663a2b390e..9bfb70bf42 100644
--- a/scene/gui/file_dialog.cpp
+++ b/scene/gui/file_dialog.cpp
@@ -47,6 +47,7 @@ void FileDialog::_notification(int p_what) {
 	if (p_what == NOTIFICATION_ENTER_TREE) {
 
 		refresh->set_icon(get_icon("reload"));
+		dir_up->set_icon(get_icon("ArrowUp", "EditorIcons"));
 	}
 
 	if (p_what == NOTIFICATION_DRAW) {
@@ -122,6 +123,9 @@ void FileDialog::update_dir() {
 	if (drives->is_visible()) {
 		drives->select(dir_access->get_current_drive());
 	}
+
+	// Deselect any item, to make "Select Current Folder" button text by default.
+	deselect_items();
 }
 
 void FileDialog::_dir_entered(String p_dir) {
@@ -156,6 +160,10 @@ void FileDialog::_post_popup() {
 		tree->grab_focus();
 
 	set_process_unhandled_input(true);
+
+	// For open dir mode, deselect all items on file dialog open.
+	if (mode == MODE_OPEN_DIR)
+		deselect_items();
 }
 
 void FileDialog::_action_pressed() {
@@ -296,6 +304,37 @@ bool FileDialog::_is_open_should_be_disabled() {
 	return false;
 }
 
+void FileDialog::_go_up() {
+
+	dir_access->change_dir("..");
+	update_file_list();
+	update_dir();
+}
+
+void FileDialog::deselect_items() {
+
+	// Clear currently selected items in file manager.
+	tree->deselect_all();
+
+	// And change get_ok title.
+	if (!tree->is_anything_selected()) {
+		get_ok()->set_disabled(_is_open_should_be_disabled());
+
+		switch (mode) {
+
+			case MODE_OPEN_FILE:
+			case MODE_OPEN_FILES:
+				get_ok()->set_text(TTR("Open"));
+				get_ok()->set_disabled(false);
+				break;
+
+			case MODE_OPEN_DIR:
+				get_ok()->set_text(TTR("Select Current Folder"));
+				get_ok()->set_disabled(false);
+				break;
+		}
+	}
+}
 void FileDialog::_tree_selected() {
 
 	TreeItem *ti = tree->get_selected();
@@ -306,6 +345,8 @@ void FileDialog::_tree_selected() {
 	if (!d["dir"]) {
 
 		file->set_text(d["name"]);
+	} else if (mode == MODE_OPEN_DIR) {
+		get_ok()->set_text(TTR("Select this Folder"));
 	}
 
 	get_ok()->set_disabled(_is_open_should_be_disabled());
@@ -349,7 +390,7 @@ void FileDialog::update_file_list() {
 
 	while ((item = dir_access->get_next(&isdir)) != "") {
 
-		if (item == ".")
+		if (item == "." || item == "..")
 			continue;
 
 		ishidden = dir_access->current_is_hidden();
@@ -362,11 +403,6 @@ void FileDialog::update_file_list() {
 		}
 	}
 
-	if (dirs.find("..") == NULL) {
-		//may happen if lacking permissions
-		dirs.push_back("..");
-	}
-
 	dirs.sort_custom<NaturalNoCaseComparator>();
 	files.sort_custom<NaturalNoCaseComparator>();
 
@@ -742,6 +778,8 @@ void FileDialog::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("_make_dir_confirm"), &FileDialog::_make_dir_confirm);
 	ClassDB::bind_method(D_METHOD("_update_file_list"), &FileDialog::update_file_list);
 	ClassDB::bind_method(D_METHOD("_update_dir"), &FileDialog::update_dir);
+	ClassDB::bind_method(D_METHOD("_go_up"), &FileDialog::_go_up);
+	ClassDB::bind_method(D_METHOD("deselect_items"), &FileDialog::deselect_items);
 
 	ClassDB::bind_method(D_METHOD("invalidate"), &FileDialog::invalidate);
 
@@ -789,6 +827,12 @@ FileDialog::FileDialog() {
 	set_title(RTR("Save a File"));
 
 	HBoxContainer *hbc = memnew(HBoxContainer);
+
+	dir_up = memnew(ToolButton);
+	dir_up->set_tooltip(TTR("Go to parent folder"));
+	hbc->add_child(dir_up);
+	dir_up->connect("pressed", this, "_go_up");
+
 	hbc->add_child(memnew(Label(RTR("Path:"))));
 	dir = memnew(LineEdit);
 	hbc->add_child(dir);
@@ -833,6 +877,7 @@ FileDialog::FileDialog() {
 	//cancel->connect("pressed", this,"_cancel_pressed");
 	tree->connect("cell_selected", this, "_tree_selected", varray(), CONNECT_DEFERRED);
 	tree->connect("item_activated", this, "_tree_db_selected", varray());
+	tree->connect("nothing_selected", this, "deselect_items");
 	dir->connect("text_entered", this, "_dir_entered");
 	file->connect("text_entered", this, "_file_entered");
 	filter->connect("item_selected", this, "_filter_selected");
diff --git a/scene/gui/file_dialog.h b/scene/gui/file_dialog.h
index 6281e88731..ca3d9f54b2 100644
--- a/scene/gui/file_dialog.h
+++ b/scene/gui/file_dialog.h
@@ -86,6 +86,8 @@ private:
 	DirAccess *dir_access;
 	ConfirmationDialog *confirm_save;
 
+	ToolButton *dir_up;
+
 	ToolButton *refresh;
 
 	Vector<String> filters;
@@ -111,6 +113,7 @@ private:
 	void _filter_selected(int);
 	void _make_dir();
 	void _make_dir_confirm();
+	void _go_up();
 
 	void _update_drives();
 
@@ -156,6 +159,8 @@ public:
 
 	void invalidate();
 
+	void deselect_items();
+
 	FileDialog();
 	~FileDialog();
 };
diff --git a/scene/gui/tree.cpp b/scene/gui/tree.cpp
index 57c6737848..ab12d123ba 100644
--- a/scene/gui/tree.cpp
+++ b/scene/gui/tree.cpp
@@ -1923,9 +1923,6 @@ int Tree::propagate_mouse_event(const Point2i &p_pos, int x_ofs, int y_ofs, bool
 				c = c->next;
 				item_h += child_h;
 			}
-
-			if (!c && !p_mod->get_shift() && !p_mod->get_control() && !p_mod->get_command() && !click_handled && p_button != BUTTON_RIGHT)
-				emit_signal("nothing_selected");
 		}
 	}
 
@@ -2602,6 +2599,11 @@ void Tree::_gui_input(Ref<InputEvent> p_event) {
 					if (drag_touching) {
 						set_physics_process(true);
 					}
+
+					if (b->get_button_index() == BUTTON_LEFT) {
+						if (get_item_at_position(b->get_position()) == NULL && !b->get_shift() && !b->get_control() && !b->get_command())
+							emit_signal("nothing_selected");
+					}
 				}
 
 			} break;
@@ -3046,6 +3048,25 @@ void Tree::set_select_mode(SelectMode p_mode) {
 	select_mode = p_mode;
 }
 
+void Tree::deselect_all() {
+
+	TreeItem *item = get_next_selected(get_root());
+	while (item) {
+		item->deselect(selected_col);
+		item = get_next_selected(get_root());
+	}
+
+	selected_item = NULL;
+	selected_col = -1;
+
+	update();
+}
+
+bool Tree::is_anything_selected() {
+
+	return (selected_item != NULL);
+}
+
 void Tree::clear() {
 
 	if (blocked > 0) {
diff --git a/scene/gui/tree.h b/scene/gui/tree.h
index 64d6016942..112de3165f 100644
--- a/scene/gui/tree.h
+++ b/scene/gui/tree.h
@@ -546,6 +546,8 @@ public:
 	int get_selected_column() const;
 	int get_pressed_button() const;
 	void set_select_mode(SelectMode p_mode);
+	void deselect_all();
+	bool is_anything_selected();
 
 	void set_columns(int p_columns);
 	int get_columns() const;