Provide possibility to change whitespace in ComboBox

[Lesurglesum]

Sometimes between a ComboBox Text and its arrow-button is some whitespace which you cannot get rid of. The computePrefWidth method of the anonymous class ListView of ComboBoxListViewSkin seems to be responsible for this whitespace. In particular this line of code:

openjdk-jfx/modules/javafx.controls/src/main/java/javafx/scene/control/skin/ComboBoxListViewSkin.java

Line 527 in 1ba0255

pw = Math.max(comboBox.getWidth(), skin.getMaxCellWidth(rowsToMeasure) + 30);

On Stack Overflow is a question which addresses this problem already.

It would be nice if you could change this behaviour without the need to extend ComboBoxListViewSkin and provide your own Skin to ComboBox.