Added secondary mode button logic; added arrow bi-directionality; cleaned up primary button box

src/data/events/brushes/dual_arrow.py

@@ -0,0 +1,24 @@
+# Python imports
+
+# Lib imports
+import cairo
+
+# Application imports
+from .arrow import Arrow
+
+
+
+class DualArrow(Arrow):
+    def __init__(self):
+        super(DualArrow, self).__init__()
+
+
+    def process(self, brush: cairo.Context):
+        self.set_brush_data(brush)
+
+        x1, y1 = self.points[0].x, self.points[0].y
+        x2, y2 = self.points[1].x, self.points[1].y
+
+        self.draw_start_arrow_head(brush, x1, y1, x2, y2)
+        self.draw_arrow_body(brush, x1, y1, x2, y2)
+        self.draw_end_arrow_head(brush, x1, y1, x2, y2)