Taskbar is suddenly double height. I know how to drag from the edge to make it taller or shorter but I am not able to make it shorter.
Any suggestions?

The NextSTART taskbar will be at least as tall as necessary to accommodate the largest element in it. Check the size of your Quick Launch and Tasklist icons, etc...

What I found is that some themes stay to high and some themes stay one line. I fixed the problem by using a theme that is one line high.

It depends on the contents of the taskbar in conjunction to the current theme. If you enable the date on the system tray button, for instance, the button will be two lines high. Whether that fits onto a single row taskbar depends on other factors, such as tasklist icon size and certain other theme settings related to the taskbar container.

If one of the elements does not fit, then the taskbar is automatically re-sized by one tasklist row in order to fit everything. The unit here is tasklist rows.

Here is the taskbar at its lowest.


Here I have changed nothing but the theme and it gets bigger.


So this happens because some element on the bar is to big for it to stay one line correct?
Just making sure I understand:)

Yes, even if only by a single pixel. For instance, in the example screenshots you posted above: that systray button is showing both the date and the time, which makes it a double line button. Now, it might *look* like that systray button would fit into a single row taskbar, but, as I said above, a difference of a single pixel might be enough to trigger the automatic taskbar re-size.

You can test this: right click on the systray button and select 'Hide Date'. If I'm right and the systray button is the culprit, the taskbar will automatically shrink to single row.

You see, the Date feature in the systray button is quite recent, most themes were made when only the time could appear in the systray button.