Filtering allows certain files to be masked from view in the Files pane; only the files you specify (and folders) will be visible. This helps find files quickly, particularly in folders which contain a large number of files, such as the Windows folder. Filtering can be applied on a tab-by-tab basis.
Ctrl + Shift + F
The filter specified is in the form of a wildcard pattern, in a manner similar to Wildcard Select. See here for a description of wildcard patterns. When the pattern is set (by clicking OK), then the filter is applied automatically to the current tab and only those files which are a match for the wildcard pattern are displayed.
The Set Filter… dialog drop-down shows previous wildcard patterns used in filtering.
This menu item is a toggle which enables/disables filtering; filtering (when enabled) always uses the last set wildcard pattern, as shown on the Set Filter… (Filter Results) dialog.
When filtering is enabled, the following image is present in the center of the Files pane:
If filtering is disabled, the files which are now visible may be placed at the top of the file list; a Refresh may need to be done in order to sort the files.