flip selected segment in drag select appropriately

CHANGELOG.md

@@ -7,6 +7,7 @@
 
 ### Added
 
+- Make track section select easier by flipping the selection of single track appropriately.
 - Automatically select connected track when deleting a single track segment.
 - Current brickrail layout path now displayed in window title
 - Added configurable motor and sensor parameters to Trains (https://github.com/Novakasa/brickrail/issues/116, https://github.com/Novakasa/brickrail/issues/85)

brickrail-gui/layout/layout_info.gd

@@ -572,14 +572,11 @@ func draw_select(draw_cell):
 	var track = drawing_last.create_track(slot0, slot1)
 	if track.get_orientation() in drawing_last.tracks:
 		track = drawing_last.tracks[track.get_orientation()].get_directed_to(slot1)
-		if drag_selection == null:
-			drag_selection = LayoutSection.new()
-			drag_selection.select()
-			drag_selection.connect("unselected", self, "_on_drawing_section_unselected")
-			drag_selection.name="drag_selection"
-			add_child(drag_selection)
-		else:
-			if not drag_selection.can_add_track(track):
+		if not drag_selection.can_add_track(track):
+			if drag_selection.flip().can_add_track(track):
+				drag_selection = drag_selection.flip()
+				drag_selection.select()
+			else:
 				return
 		drag_selection.add_track(track)
 		drawing_last2 = drawing_last