diff --git a/.gitignore b/.gitignore
index 3a30800..581e7b2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,4 @@ AppDir
 NMReval*.zsync
 .idea
 *.zs-old
+docs
diff --git a/src/gui_qt/_py/eval_expr_dialog.py b/src/gui_qt/_py/eval_expr_dialog.py
index d70a5ed..5bda16f 100644
--- a/src/gui_qt/_py/eval_expr_dialog.py
+++ b/src/gui_qt/_py/eval_expr_dialog.py
@@ -1,10 +1,11 @@
 # -*- coding: utf-8 -*-
 
-# Form implementation generated from reading ui file 'resources/_ui/eval_expr_dialog.ui'
+# Form implementation generated from reading ui file 'src/resources/_ui/eval_expr_dialog.ui'
 #
-# Created by: PyQt5 UI code generator 5.12.3
+# Created by: PyQt5 UI code generator 5.15.9
 #
-# WARNING! All changes made in this file will be lost!
+# WARNING: Any manual changes made to this file will be lost when pyuic5 is
+# run again.  Do not edit this file unless you know what you are doing.
 
 
 from PyQt5 import QtCore, QtGui, QtWidgets
@@ -36,14 +37,14 @@ class Ui_CalcDialog(object):
         self.label_2 = QtWidgets.QLabel(self.page)
         self.label_2.setObjectName("label_2")
         self.verticalLayout_2.addWidget(self.label_2)
-        self.listWidget = QtWidgets.QListWidget(self.page)
+        self.listWidget = QListWidgetSelect(self.page)
         sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Preferred, QtWidgets.QSizePolicy.MinimumExpanding)
         sizePolicy.setHorizontalStretch(0)
         sizePolicy.setVerticalStretch(0)
         sizePolicy.setHeightForWidth(self.listWidget.sizePolicy().hasHeightForWidth())
         self.listWidget.setSizePolicy(sizePolicy)
         self.listWidget.setEditTriggers(QtWidgets.QAbstractItemView.NoEditTriggers)
-        self.listWidget.setSelectionMode(QtWidgets.QAbstractItemView.SingleSelection)
+        self.listWidget.setSelectionMode(QtWidgets.QAbstractItemView.ExtendedSelection)
         self.listWidget.setObjectName("listWidget")
         self.verticalLayout_2.addWidget(self.listWidget)
         self.overwrite_checkbox = QtWidgets.QCheckBox(self.page)
@@ -202,7 +203,7 @@ class Ui_CalcDialog(object):
         self.label_8.setBuddy(self.line_doubleSpinBox)
 
         self.retranslateUi(CalcDialog)
-        self.stackedWidget.setCurrentIndex(2)
+        self.stackedWidget.setCurrentIndex(0)
         QtCore.QMetaObject.connectSlotsByName(CalcDialog)
         CalcDialog.setTabOrder(self.calc_edit, self.listWidget)
         CalcDialog.setTabOrder(self.listWidget, self.overwrite_checkbox)
@@ -237,4 +238,5 @@ class Ui_CalcDialog(object):
         self.label_11.setText(_translate("CalcDialog", "Style"))
         self.label.setText(_translate("CalcDialog", "Expressions are evaluated line by line and change previous values"))
 from ..lib.delegates import ColorListEditor, LineStyleEditor, SymbolStyleEditor
+from ..lib.listwidget import QListWidgetSelect
 from ..lib.namespace import QNamespaceWidget
diff --git a/src/gui_qt/lib/listwidget.py b/src/gui_qt/lib/listwidget.py
new file mode 100644
index 0000000..c4128da
--- /dev/null
+++ b/src/gui_qt/lib/listwidget.py
@@ -0,0 +1,16 @@
+from ..Qt import QtWidgets, QtGui, QtCore
+
+
+class QListWidgetSelect(QtWidgets.QListWidget):
+    def __init__(self, parent=None):
+        super().__init__(parent=parent)
+
+    def keyPressEvent(self, evt: QtGui.QKeyEvent):
+        if evt.key() == QtCore.Qt.Key.Key_Space:
+            for idx in self.selectedIndexes():
+                item = self.itemFromIndex(idx)
+                cs = item.checkState()
+                item.setCheckState(QtCore.Qt.CheckState.Unchecked if cs == QtCore.Qt.CheckState.Checked
+                                   else QtCore.Qt.CheckState.Checked)
+        else:
+            super().keyPressEvent(evt)
diff --git a/src/resources/_ui/eval_expr_dialog.ui b/src/resources/_ui/eval_expr_dialog.ui
index c3f7791..c483d3f 100644
--- a/src/resources/_ui/eval_expr_dialog.ui
+++ b/src/resources/_ui/eval_expr_dialog.ui
@@ -27,7 +27,7 @@
        <item>
         <widget class="QStackedWidget" name="stackedWidget">
          <property name="currentIndex">
-          <number>2</number>
+          <number>0</number>
          </property>
          <widget class="QWidget" name="page">
           <layout class="QVBoxLayout" name="verticalLayout_2">
@@ -54,7 +54,7 @@
             </widget>
            </item>
            <item>
-            <widget class="QListWidget" name="listWidget">
+            <widget class="QListWidgetSelect" name="listWidget">
              <property name="sizePolicy">
               <sizepolicy hsizetype="Preferred" vsizetype="MinimumExpanding">
                <horstretch>0</horstretch>
@@ -65,7 +65,7 @@
               <set>QAbstractItemView::NoEditTriggers</set>
              </property>
              <property name="selectionMode">
-              <enum>QAbstractItemView::SingleSelection</enum>
+              <enum>QAbstractItemView::ExtendedSelection</enum>
              </property>
             </widget>
            </item>
@@ -414,6 +414,11 @@
    <header>..lib.namespace</header>
    <container>1</container>
   </customwidget>
+  <customwidget>
+   <class>QListWidgetSelect</class>
+   <extends>QListWidget</extends>
+   <header>..lib.listwidget</header>
+  </customwidget>
  </customwidgets>
  <tabstops>
   <tabstop>calc_edit</tabstop>