i have a new installation of Devuan Ascii 64bit on my computer with XFCE4 as Desktop.

Noticed that on latest Thunderbird 68.2.2 it would not allow me to change the width of the columns in the mail section or in the feed reader section.
Whenever i hover over the separators, the icon would not change from an arrow to the icon meant for changing the width - it remains the same pointer arrow.

Any idea?

Thanks