diff --git a/FlatCAM.py b/FlatCAM.py
index 546877a3..33b2b7c7 100644
--- a/FlatCAM.py
+++ b/FlatCAM.py
@@ -1,7 +1,7 @@
 import sys
 import os
 
-from PyQt5 import QtWidgets, QtGui
+from PyQt5 import QtWidgets
 from PyQt5.QtCore import QSettings, Qt
 from FlatCAMApp import App
 from flatcamGUI import VisPyPatches
diff --git a/FlatCAMApp.py b/FlatCAMApp.py
index e3d570d2..cc33ca1b 100644
--- a/FlatCAMApp.py
+++ b/FlatCAMApp.py
@@ -9543,7 +9543,7 @@ class App(QtCore.QObject):
 
         _filter_ = "Gerber Files (*.gbr *.ger *.gtl *.gbl *.gts *.gbs *.gtp *.gbp *.gto *.gbo *.gm1 *.gml *.gm3 *" \
                    ".gko *.cmp *.sol *.stc *.sts *.plc *.pls *.crc *.crs *.tsm *.bsm *.ly2 *.ly15 *.dim *.mil *.grb" \
-                   "*.top *.bot *.smt *.smb *.sst *.ssb *.spt *.spb *.pho *.gdo *.art *.gbd *.gb*);;" \
+                   "*.top *.bot *.smt *.smb *.sst *.ssb *.spt *.spb *.pho *.gdo *.art *.gbd);;" \
                    "Protel Files (*.gtl *.gbl *.gts *.gbs *.gto *.gbo *.gtp *.gbp *.gml *.gm1 *.gm3 *.gko);;" \
                    "Eagle Files (*.cmp *.sol *.stc *.sts *.plc *.pls *.crc *.crs *.tsm *.bsm *.ly2 *.ly15 *.dim " \
                    "*.mil);;" \
@@ -9570,8 +9570,7 @@ class App(QtCore.QObject):
                                     color=QtGui.QColor("gray"))
 
         if len(filenames) == 0:
-            self.inform.emit('[WARNING_NOTCL] %s' %
-                             _("Open Gerber cancelled."))
+            self.inform.emit('[WARNING_NOTCL] %s' % _("Open Gerber cancelled."))
         else:
             for filename in filenames:
                 if filename != '':
diff --git a/README.md b/README.md
index e38cf11e..8fe6e57d 100644
--- a/README.md
+++ b/README.md
@@ -16,6 +16,9 @@ CAD program, and create G-Code for Isolation routing.
 - fix for contextual menus on canvas when using PyQt versions > 5.12.1
 - decision on which mouse button to use for panning is done now once when setting the plotcanvas
 - fix to work with Python 3.8 (closing the application)
+- fixed bug in Gerber parser that allowed loading as Gerber of a file that is not a Gerber
+- fixed a bug in extension detection for Gerber files that allowed in the filtered list files that extension *.gb*
+- added a processEvents method in the Gerber parser parse_lines() method
 
 4.04.2020 
 
diff --git a/flatcamParsers/ParseGerber.py b/flatcamParsers/ParseGerber.py
index deba943e..bad7b97d 100644
--- a/flatcamParsers/ParseGerber.py
+++ b/flatcamParsers/ParseGerber.py
@@ -1,4 +1,4 @@
-
+from PyQt5 import QtWidgets
 from camlib import Geometry, arc, arc_angle, ApertureMacro
 import FlatCAMApp
 
@@ -1416,6 +1416,8 @@ class Gerber(Geometry):
                 # ######### Line did not match any pattern. Warn user.  ##########
                 # ################################################################
                 log.warning("Line ignored (%d): %s" % (line_num, gline))
+                # provide the app with a way to process the GUI events when in a blocking loop
+                QtWidgets.QApplication.processEvents()
 
             try:
                 path_length = len(path)
@@ -1475,7 +1477,7 @@ class Gerber(Geometry):
                 sol_geo_length = 1
 
             try:
-                if buff_length == 0 and sol_geo_length == 0:
+                if buff_length == 0 and sol_geo_length in [0, 1]:
                     log.error("Object is not Gerber file or empty. Aborting Object creation.")
                     return 'fail'
             except TypeError as e: