The palette window? There are many palettes in Photoshop. Is the palette window you have a problem with a palette installed by some Photoshop extension you have installed? What you show looks like that may be the cast and the Extension is have a problem with CC 2018. Check with the extension developer see if they have a version that works with CC 2018. Make sure you tell them your using a Mac.
I tried the same extension on cc2014 and it works perfectly
maybe the problem is cc2018?
Have you ask the developer if they have a version tat work in CC 2018. There have been many System and Photoshop changes since CC 2014 and CC 2018 has at least three updates. Compatibility problem between version of Photoshop is not uncommon.
I contacted the developer
he told me that it is compatible with photoshop cc2018
The problem creates it only with the palette panels
with the dialog panels it does not do this problem.
Who programmed the problem palette Adobe or the Extension developer? The developer may have a problem with how the implemented Palette works in CC 2018. Some Adobe interfaces may have been changed the extension developer may need to make a changed for CC 2018 you state it works in CC 204.