diff --git a/pixelocr/gui/glyphdbedit.py b/pixelocr/gui/glyphdbedit.py
index 44ccf39..a91a94c 100644
--- a/pixelocr/gui/glyphdbedit.py
+++ b/pixelocr/gui/glyphdbedit.py
@@ -39,7 +39,8 @@ class Column(object):
     to_display = str
     to_value = str
 
-    def __init__(self, header, field_name):
+    def __init__(self, document, header, field_name):
+        self.document = document
         self.header = header
         self.field_name = field_name
 
@@ -103,45 +104,47 @@ class ColorColumn(Column):
 
 
 class GlyphDBModel(QAbstractTableModel):
-    COLUMNS = [
-        TextColumn('Text', 'text'),
-        IntColumn('Elevation', 'elevation'),
-        CheckBoxColumn('B', 'bold'),
-        CheckBoxColumn('I', 'italic'),
-        ColorColumn('Color', 'color'),
-        DateColumn('Date added', 'date_added'),
-    ]
-
     def __init__(self, document, parent=None):
         super().__init__(parent)
         self.document = document
         self.glyphdb = document.glyphdb
-        self.sortColumn = len(self.COLUMNS) - 1  # date_add ed
+        self.columns = self.createColumns()
+        self.sortColumn = len(self.columns) - 1  # date_add ed
         self.sortOrder = Qt.DescendingOrder
         self.values = list(self.glyphdb.values())
         self.updateData()
 
+    def createColumns(self):
+        return [
+            TextColumn(self.document, 'Text', 'text'),
+            IntColumn(self.document, 'Elevation', 'elevation'),
+            CheckBoxColumn(self.document, 'B', 'bold'),
+            CheckBoxColumn(self.document, 'I', 'italic'),
+            ColorColumn(self.document, 'Color', 'color'),
+            DateColumn(self.document, 'Date added', 'date_added'),
+        ]
+
     def flags(self, index):
-        column = self.COLUMNS[index.column()]
+        column = self.columns[index.column()]
         return super().flags(index) | column.flags
 
     def rowCount(self, parent):
         return len(self.values)
 
     def columnCount(self, parent):
-        return len(self.COLUMNS)
+        return len(self.columns)
 
     def headerData(self, section, orientation, role):
         if orientation == Qt.Horizontal and role == Qt.DisplayRole:
-            return self.COLUMNS[section].header
+            return self.columns[section].header
 
     def data(self, index, role):
-        column = self.COLUMNS[index.column()]
+        column = self.columns[index.column()]
         glyph_data = self.values[index.row()]
         return column.data(glyph_data, role)
 
     def setData(self, index, value, role):
-        column = self.COLUMNS[index.column()]
+        column = self.columns[index.column()]
         glyph_data = self.values[index.row()]
         self.glyphdb.remove(glyph_data)
         column.setData(glyph_data, value, role)
@@ -167,7 +170,7 @@ class GlyphDBModel(QAbstractTableModel):
 
     def updateData(self):
         self.layoutAboutToBeChanged.emit()
-        column = self.COLUMNS[self.sortColumn]
+        column = self.columns[self.sortColumn]
         reverse = self.sortOrder == Qt.DescendingOrder
         if len(self.values) != len(self.glyphdb.values()):
             self.values = self.glyphdb.values()