The issue is that the text is not displayed horizontally and it is hard to read, and javaFX does not provide a solution to it, actually there is feature request to it https://javafx-jira.kenai.com/browse/RT-19547 but it seems that it will not happen soon.
I found some workarounds to it, but they have many issues such as the text doesn't properly resize the tab width, so I'm going to describe the workaround that I did, hoping that it could be helpful to you.
A solution that I found from this post http://stackoverflow.com/questions/16708578/javafx-2-0-tabpane-tabs-at-left-and-keep-tab-header-horizontal , mentions to add the following style:
Which works fine:
But what if you have multiple tabs in your application and this tabs do not have the tabs by a side, it will also rotate the text of this tabs and will complicate everything.
Another issue is, if the characters of the text increases the size also increases but not only its width but also its height:
Due to all this issues this workaround and others seem to work fine only in certain scenarios.
My workaround is not better than them, but it tries to avoid these issues.
First, only rotate the tabs you want to rotate, to do this create a CSS class:
Then add it to the tabs objects you want to rotate:
Then create a CSS class to handle the size for the TabPane in which you are rotating the tabs:
Add this class to the TabPane object:
With this you will restrict the size of your tabs and they will not get bigger if the text increases. The limitation it has is that the amount of characters depends on the size you set to the TabPane object.
If you have a different solution before this issue is fixed tell me about it.