Split up PreferencesUI.py into individual files for each class, then fixed the imports everywhere that broke because of this.

flatcamGUI/preferences/ToolsSubPrefGroupUI.py

@@ -0,0 +1,27 @@
+from PyQt5 import QtWidgets
+
+from flatcamGUI.GUIElements import FCCheckBox
+from flatcamGUI.preferences.OptionsGroupUI import OptionsGroupUI
+
+
+class ToolsSubPrefGroupUI(OptionsGroupUI):
+    def __init__(self, decimals=4, parent=None):
+
+        super(ToolsSubPrefGroupUI, self).__init__(self)
+
+        self.setTitle(str(_("Substractor Tool Options")))
+        self.decimals = decimals
+
+        # ## Subtractor Tool Parameters
+        self.sublabel = QtWidgets.QLabel("<b>%s:</b>" % _("Parameters"))
+        self.sublabel.setToolTip(
+            _("A tool to substract one Gerber or Geometry object\n"
+              "from another of the same type.")
+        )
+        self.layout.addWidget(self.sublabel)
+
+        self.close_paths_cb = FCCheckBox(_("Close paths"))
+        self.close_paths_cb.setToolTip(_("Checking this will close the paths cut by the Geometry substractor object."))
+        self.layout.addWidget(self.close_paths_cb)
+
+        self.layout.addStretch()