Fixed #147. Had a circular dependency import.

FlatCAMDraw.py

@@ -1322,7 +1322,17 @@ class FlatCAMDraw(QtCore.QObject):
         self.replot()
 
     def buffer(self, buf_distance):
-        pre_buffer = cascaded_union([t.geo for t in self.get_selected()])
+        selected = self.get_selected()
+
+        if len(selected) == 0:
+            self.app.inform.emit("[warning] Nothing selected for buffering.")
+            return
+
+        if not isinstance(buf_distance, float):
+            self.app.inform.emit("[warning] Invalid distance for buffering.")
+            return
+
+        pre_buffer = cascaded_union([t.geo for t in selected])
         results = pre_buffer.buffer(buf_distance)
         self.add_shape(DrawToolShape(results))
 

FlatCAMTool.py

@@ -3,9 +3,8 @@ from shapely.geometry import Point
 from shapely import affinity
 from math import sqrt
 
-import FlatCAMApp
 from GUIElements import *
-from FlatCAMObj import FlatCAMGerber, FlatCAMExcellon
+from FlatCAMObj import *
 
 
 class FlatCAMTool(QtGui.QWidget):