I'm pretty sure that is the scrollbar.
If you must adjust your arrow button size with scripting, here is a simple recursive function that will do it:
from com.inductiveautomation.factorypmi.application.components.util import HoldDownArrowButton
from com.inductiveautomation.factorypmi.application.components.tabstrip import LeftRightArrowPanel
from java.awt import Dimension
tabStrip = system.gui.getParentWindow(event).getComponentForPath('Root Container.Tab Strip')
arrowHeight = 50
arrowWidth = 50
def tabStripArrowEditor(tabStrip):
if tabStrip.componentCount > 0:
for component in tabStrip.getComponents():
if isinstance(component, LeftRightArrowPanel):
size = Dimension(arrowWidth*2,arrowHeight)
component.setPreferredSize(size)
component.setSize(size)
tabStripArrowEditor(component)
return
elif isinstance(component, HoldDownArrowButton):
size = Dimension(arrowWidth,arrowHeight)
component.setPreferredSize(size)
component.setSize(size)
else:
tabStripArrowEditor(component)
tabStripArrowEditor(tabStrip)
Before and after result:
Note: the height will be limited by the height of the tab strip