Transfers among Inventory files

How can I coalesce items in my inventory in new files? If I want to move stuff from file1 to file2, and file1 and file 2 are really far apart, how can I make that transfer? I can't drag the item while I'm scrolling down. If I want all shirts in one file I can search for "shirts" and then highlight them and transfer them all, but I may want to move items that don't all have the same name and can't be collected by a search.

Much gratitude for answers.

Using the menus of the Inventory window, click File / New Window -- that will open a second inventory window, which will help in moving things around.