EmEditor Professional (64-bit) Version 20.0.901 W10, 1803
By minimize the window, also minimized the other window (when I made a new group before). By double click on taskbar to activate it again, both windows came back. If I have more groups, the last 2 are “glue/stick”.
for example W1 = window one W1-2 = new window (group) made from W1 W1-2-3 = new window (group) made from W1-2