Tabs move to bottom row when clicked. Possible to disable?

A new feature with Spark 2.6.3 is that tabs move to the bottom row whenever they are clicked. Please see the attached photo. Is there a way to disable this feature? It’s frustrating when everything is moved around each time you click a tab. I would like things to stay where they are.

It is not a feature. This was reported by me a while ago, but was marked as Won’t Fix as it is a very complex issue related to how Java is stacking the tabs - SPARK-1265. Actually if you try some Substance skins, it will happen less as the fonts and tabs in Substance are smaller. But with Substance you will see more tabs stretching.

I can not advise to use Substance skins. They are included in the distribution for some reason, but buggy (e.g. they break file transfer modes) and unsupported. Since Substance is a open source lib that is not developed anymore, there is little hope to get that fixed unless someone takes the whole project.