Currently, MarginNote has no global search mask to find documents by “file content”. (MarginNote can only find documents by “file name”.)
Please provide a search mask to find documents by “file content”. For example, find all documents which has the word “pattern” within a directory of documents. Look at the global search mask of DEVONthink for inspiration.
I think the “global search mask” must be within the master page for usability reasons. The master-page should be viewed as a left sidebar (which can be fixed on the left side) and look like a finder, where we can list all “documents/categories/tags/study”. Because, for example, if I search the word “pattern” then it should list all documents on the left side where I can switch or open a new tab (on the detail-page) with the founded document. Look at Improve overall master-detail page/navigation for better master-details-navigation.