Description of the Issue

Language-->User defined language-->define your language
1-the label for button "Undock" is not possible to translate (it is not present in the master English.xml)
2- the label of button "dock" is translated only when you get into the form the first time; if you press "dock" and "undock", the label "Dock" appears untranslated
3-in the form user-defined, in undock-mode, there is not any scrollbars

Steps to Reproduce the Issue

1. Language-->User defined language-->define your language (the first time the label "Dock" is translated)
   

2. press "Dock": the button "Undock" appears untranslated
   

3. Press "undock": the button "Dock" appears untranslated

4. when the form is Undocked, there is not any scrollbars

Expected Behavior

1. Include the label "undock" in the master English.xml
2. refresh the buttons Dock/Undock with the right translation
3. insert a scrollbar in the form in "undock-MODE"

Actual Behavior

Labels not translated for "undock", the translation for "Dock" appears only the first time, scrollbar missing in "undock-mode"

Debug Information

Notepad++ v7.8.5 (32-bit)
Build time : Mar 4 2020 - 11:04:20
Path : C:\Program Files (x86)\Notepad++\notepad++.exe
Admin mode : OFF
Local Conf mode : OFF
OS Name : Windows 10 Enterprise (64-bit)
OS Version : 1903
OS Build : 18362.657
Plugins : ComparePlugin.dll mimeTools.dll NppConverter.dll NppExport.dll Translate.dll XMLTools.dll