A few small adjustments to file dialogs:

a) Added Backspace key support for Tree-based file dialog.
b) Fixed issue inability to select a folder in project manager (always previous folder was selected instead).
c) Open Directory mode: changed "Open" to "Select Current Folder"
d) Block "Open" button when inappropriate content is selected (for example, file when in open folder mode, or folder when in open files mode)

2 files changed, 30 insertions, 3 deletions

diff --git a/scene/gui/file_dialog.cpp b/scene/gui/file_dialog.cpp
index 6aba535572..663a2b390e 100644
--- a/scene/gui/file_dialog.cpp
+++ b/scene/gui/file_dialog.cpp
@@ -85,6 +85,10 @@ void FileDialog::_unhandled_input(const Ref<InputEvent> &p_event) {
 
 					invalidate();
 				} break;
+				case KEY_BACKSPACE: {
+
+					_dir_entered("..");
+				} break;
 				default: { handled = false; }
 			}
 
@@ -189,7 +193,7 @@ void FileDialog::_action_pressed() {
 		TreeItem *item = tree->get_selected();
 		if (item) {
 			Dictionary d = item->get_metadata(0);
-			if (d["dir"]) {
+			if (d["dir"] && d["name"] != "..") {
 				path = path.plus_file(d["name"]);
 			}
 		}
@@ -272,6 +276,26 @@ void FileDialog::_cancel_pressed() {
 	hide();
 }
 
+bool FileDialog::_is_open_should_be_disabled() {
+
+	if (mode == MODE_OPEN_ANY || mode == MODE_SAVE_FILE)
+		return false;
+
+	TreeItem *ti = tree->get_selected();
+	// We have something that we can't select?
+	if (!ti)
+		return true;
+
+	Dictionary d = ti->get_metadata(0);
+
+	// Opening a file, but selected a folder? Forbidden.
+	if (((mode == MODE_OPEN_FILE || mode == MODE_OPEN_FILES) && d["dir"]) || // Flipped case, also forbidden.
+			(mode == MODE_OPEN_DIR && !d["dir"]))
+		return true;
+
+	return false;
+}
+
 void FileDialog::_tree_selected() {
 
 	TreeItem *ti = tree->get_selected();
@@ -283,6 +307,8 @@ void FileDialog::_tree_selected() {
 
 		file->set_text(d["name"]);
 	}
+
+	get_ok()->set_disabled(_is_open_should_be_disabled());
 }
 
 void FileDialog::_tree_dc_selected() {
@@ -563,7 +589,7 @@ void FileDialog::set_mode(Mode p_mode) {
 			makedir->hide();
 			break;
 		case MODE_OPEN_DIR:
-			get_ok()->set_text(RTR("Open"));
+			get_ok()->set_text(RTR("Select Current Folder"));
 			set_title(RTR("Open a Directory"));
 			makedir->show();
 			break;
diff --git a/scene/gui/file_dialog.h b/scene/gui/file_dialog.h
index 34cecfe4d0..6281e88731 100644
--- a/scene/gui/file_dialog.h
+++ b/scene/gui/file_dialog.h
@@ -33,7 +33,6 @@
 #include "box_container.h"
 #include "os/dir_access.h"
 #include "scene/gui/dialogs.h"
-#include "scene/gui/dialogs.h"
 #include "scene/gui/line_edit.h"
 #include "scene/gui/option_button.h"
 #include "scene/gui/tool_button.h"
@@ -117,6 +116,8 @@ private:
 
 	void _unhandled_input(const Ref<InputEvent> &p_event);
 
+	bool _is_open_should_be_disabled();
+
 	virtual void _post_popup();
 
 protected: