in "Open file" dialog: switching a file filter does not enable/disable displayed files appropriately

when i create an QFileDialog or use QFileDialog::getOpenFilename(..) which has 2 or more file filters for the user to select from, then files in the dialog list are enabled / disabled accordingly. When the user selects another file filter from the popup list, then the files should be enabled / disabled according to the new filter. But they aren't.
As a workaround one can move to another diectory and back again or modify a file in that folder while the dialog is open.