QuickDesigner: Triggering save on integrated editor adds strange comment at eof

Steps to reproduce:

• open a QML file inside Quick Designer
• switch to Designer's integrated editor
• modify the document
• trigger save
• go to the bottom of the file

Current result:

• saving added strange comment at the end
• removing this and saving again will re-add it

the added comment is

/*##^## Designer {
    D{i:7;invisible:true}
}
 ##^##*/