Hope this question has already been asked before, googling has yielded me nothing. I've been using Scene Builder to try and code a GUI, but I can't re-size a particular button for some reason. Whenever I try to shrink it, it just snaps back to its regular size. I'm using Ubuntu Linux 12.04, if that makes any difference, and Eclipse. Thanks! 
2 Answers
You are placing your button in a ButtonBar. By default, a ButtonBar manages the size of the buttons placed in it.
By default all buttons are uniformly sized in a ButtonBar, meaning that all buttons take the width of the widest button. It is possible to opt-out of this on a per-button basis, [by] calling the setButtonUniformSize(Node, boolean) method with a boolean value of false.
If a button is excluded from uniform sizing, it is both excluded from being resized away from its preferred size, and also excluded from the measuring process, so its size will not influence the maximum size calculated for all buttons in the ButtonBar.
If you want to opt out of uniform sizing, you may need to do that in code as you may not be able to do that graphically just using the SceneBuilder UI. Or you may want to use a different container than a ButtonBar for your buttons.
Answers to follow-up questions in comments
I tried to use the button outside and resize, but it resists getting smaller.
Works for me (SceneBuilder 8 on OS X 9.5).
- Ensure that no ButtonBar is used.
- Create a new project in SceneBuilder.
- Add a StackPane as the root.
- Put a button in the StackPane
- Resize the button by dragging it's boundaries in SceneBuilder.
Does it have something to do with my OS?
High unlikely. If it did, it would be an OS specific bug. Functions like this in JavaFX should work identically across operating systems.
I'm following at code.makery.ch/library/javafx-8-tutorial/part1, and the buttons show up as a different size: i.imgur.com/gCsbTtX.png
Size of controls in JavaFX are based upon the size of the font used for those controls. JavaFX uses the default system font, unless additional styling is provided. The size of the default system font varies depending on the OS and the system settings in the OS. It could be this variation that you are detecting.
Do I need to develop on Windows instead or something?
No, that should not be the case.