draw horizontal/vertical constraint on drawLine

SketchWidget.py

@@ -111,6 +111,12 @@ class SketchWidget:
 
         if self.drawingLine is not None:
             self.drawLine(self.drawingLine)
+            if self.drawingLine.getPt(0)[0] == self.drawingLine.getPt(1)[0]:
+                self.drawVertical(Vertical(self.drawingLine, 0,
+                    self.drawingLine, 1))
+            elif self.drawingLine.getPt(0)[1] == self.drawingLine.getPt(1)[1]:
+                self.drawHorizontal(Horizontal(self.drawingLine, 0,
+                    self.drawingLine, 1))
 
         if gldrawable.is_double_buffered():
             gldrawable.swap_buffers()