Add a folder specific setting for excluding the folder from the results
generated by the quickMove search box. This can be integrated into the 
"Tab-specific properties" as a checkbox.

Created an attachment (id=8652) [details]
4.16 prerelease 10

To activate the feature you need a tab representing the folder because the UI
is in "Advanced Properties". 

# Drag the folder you want to hide on the quickfolders toolbar to create a tab
# Right-click the tab and select QuickFolders commands > tab specific
properties. this will open the "Advanced Properties" panel.
# check the box [x] Omit from quickJump / quickMove.

To hide the tab (but keep the "omit" property), you need to click on 
# QuickFolders Commands > Set Tab Category
# Select "Never Show (Folder Alias)"

Note: the only way to make the tab visible again (in order to change this
setting) is if you have other Categories defined. The Category selection
dropdown is displayed only when user-defined categories exist.

Created an attachment (id=8653) [details]
4.16 prerelease 41

Added algorithms to exclude all child folders of a tab. This way it is easy to
hide whole sub-trees from the search algorithm.

In order to test timing and detail enabled [x]Debug Mode on  QuickFolders
Settings, Advanced Tab.

then (via right-click on [x]Debug) enable:

extensions.quickfolders.debug.interface.findFolder = true
extensions.quickfolders.debug.quickMove = true

This will print additional messages on what exactly was omitted by the
quickJump algorithm in the JavaScript error console. Open error console with
CTRL+SHIFT+J or via the tools > developer tools menu.

Implemented in 4.16 = released on 01/09/2019