MHC doesn't allow CPU-speeds below 20 MHz? (muellernick)

PIC32MX7 or 5 series, both the same:If I configure the clock diagramm in MHC so I do get a CPU clock of 20 MHz or less, the displayed value gets red.I'm aware, that the xtal needs a certain frequency (8 MHz in my case) ... checkI'm aware, that the PLL-sta..