Added code

ui/modules/validators/page_text.py

@@ -0,0 +1,15 @@
+from ui.modules.updaters.page_text import update_page_index
+from modules.config import charset
+from ui.gui import Ui_MainWindow
+from PyQt5 import QtGui
+
+
+def validate_page_text(ui: Ui_MainWindow, event: QtGui.QKeyEvent, old_event):
+    old_event(event)
+    for char in ui.page_text.toPlainText():
+        if char not in charset:
+            ui.page_text.setPlainText(''.join(c for c in ui.page_text.toPlainText() if c in charset))
+            ui.page_text.moveCursor(QtGui.QTextCursor.End)
+            break
+
+    update_page_index(ui)