In the Tabbed users interface Layout tab the Page Columns control is active when the document is in read-only mode. Seems to me it should be disabled.
I confirm it with Version: 7.0.0.0.alpha0+ (x64) Build ID: 962b415edb47187737a5f05c4ff3f6724a19c564 CPU threads: 4; OS: Windows 10.0 Build 18363; UI render: Skia/Raster; VCL: win; Locale: de-DE (de_DE); UI-Language: en-GB Calc: threaded and I agree, that it shouldn't be active => NEW
code pointers: https://wiki.openoffice.org/wiki/Framework/Article/Implementation_of_the_Dispatch_API_In_SFX2 https://opengrok.libreoffice.org/xref/core/sw/sdi/swriter.sdi?r=96def0ee#7590 https://www.libreoffice.org/community/developers/