I use an old win7 computer as client to run PhotoShop 2018 remoteapp in Windows 2016 RDS Server. When I click out Color Picker window is Gradient Editor window, it shows wrong position. I checked window properties by SPY++, and found that the Color Picker window has WS_POPUP style but with both parent and owner windows. Its parent is Gradient Editor window and owner is whole photoshop top-level window. On normally win7 computer its parent should be null and owner window is Gradient Editor window.
On win10 with same RDP file, everything is ok.
My win7 rdp client version is 8.1 and I known another win7 computer with same rdp client there's no such problem.