fully worked around bug in Qt

portable_computing_toolkit_installer/ui/installer_wizard.py

@@ -41,6 +41,7 @@ class InstallerWizard(QtWidgets.QWizard):
             self.install_location.inputRejected.connect(self.install_location.clear)
         except AttributeError:
             pass #inputRejected signal added in Qt 5.12, I have 5.9
+        self.button(self.BackButton).clicked.connect(lambda x: self._location_validator.reset_state())
         self.install_location.setValidator(self._location_validator)
         self.location_page.registerField("Location*", self.install_location)
         self.browse_button.clicked.connect(self._select_location)

portable_computing_toolkit_installer/validators/location_validator.py

@@ -13,10 +13,6 @@ class Location_Validator(QtGui.QValidator):
     _previous_location = None
     def __init__(self, parent):
         super().__init__(parent)
-        """for some reason on my Linux system, selecting a directory validates the same location repatedly,
-        once for each subdir of the location.  The only way to keep it from repeatedly validating and potentially
-        opening a warning window for each subdirectory in the location path was to track this and return the same
-        value that was returned the last time it was validated."""
 
     @property
     def ntfs_location_selected(self):
@@ -49,6 +45,9 @@ class Location_Validator(QtGui.QValidator):
             input_ {str} -- The text entered in the installation location QLineEdit widget
             pos {int} -- The current location of the cursor in the QLineEdit widget
         """
+        #there is a very obnoxious, nearly 10 year old bug in QLineEdit that causes validate to be called gratitously and rapidly especially on 
+        #non-Windows platforms where it gets called every time the window focus changes.  The bug has been in Qt since at least Qt4 and it doesn't
+        #look like anyone cares to fix it, so I did my best to supress gratitious input checking and modal dialog opening
         if not input_.strip():
             _previous_location = input_
             return (QtGui.QValidator.Intermediate, input_, pos)
@@ -89,3 +88,13 @@ class Location_Validator(QtGui.QValidator):
             self._previous_location = self._location
 
         return (self._disposition, self._location, self._pos,)
+
+    @QtCore.pyqtSlot()
+    def reset_state(self):
+        """Resets the internal state of the Location_Validator, including the previously validated location
+        """
+        self._disposition = QtGui.QValidator.Intermediate
+        self._pos = 0
+        self._location = ""
+        self._ntfs_location_selected = False
+        self._previous_location = None