Sorry for the video quality. The video I uploaded was much higher resolution but seems to have been formatted down to this by the server.
Perhaps this is worthy of a new thread (to deal with the useless attach video function of this forum)?
Thanks for the video. Me and others already reported this and the answer was that it seems to be caused by updates to Windows 10 since CS v1.4.1 was released. See the back bar that remains in the target tab, CS is trying to move the tab but it can't. Also if you try to rearrange the tab position inside the same window, you'll see that it is difficult, it only works once in a while.
It is extremely annoying how opening a document in a new window works in Circuit Studio.
One would think that you could drag/drop a document from the original window to the new window, but this is not the case
It appears that the only way to open a document in a new window is to right-click an already open document and select "Open in new window", or to dock the Projects panel in the window you want to open a document in, and double click on the document.
See video for illustration of what I mean: