How to reproduce: - Open the decoder subwindow, type "spi", click the SPI PD. The PD's description will be shown. - Click on "All decoders" (i.e., the PD is no longer selected), so the description field should become empty again (it currently doesn't).
Fixed in 8447ae2a7db5d00b01b458fc7c94f99e2b3b4ce4, thanks!