How to edit Thumb image size of the Scrollbox

Hi forum,

I’m creating this scrollbox UMG element, but I cannot for the life of me figure out how to get the thumb image to scale correctly. Here is what it’s supposed to look like (my composed PNG of both the scrollbar and thumb overlayed):

But here’s what UMG ends up doing:

The thumb’s details are as follows:

As you can see, I correctly set the X and Y dimensions for the image and the preview even seems to show me the correct result.

How can I manually adjust the scale of the thumb? I don’t want the thumb to stretch from the top of the scrollbar to the bottom and get smaller the more items are in the scrollbox. I want the thumb size to always be the same, but rather scroll down through the scrollbar quicker if there’s less items in the scrollbox.


The scrollbar in slate is not designed to behave that way, so you’ll need to make a new kind of scrollbar, and modify UMG’s scrollbox to expose setting a custom external scrollbar widget to your new custom scrollbar.

Alright. Thanks. Would I need to do that through C++ code? I’ve been having some trouble getting coding to work on my end.

Yeah, this is a C++ thing. You’re going to need to become close friends with some Slate code :slight_smile:

Okay thank you. As soon as I can actually build code on my side, I’ll dive into it…

This is so frustrating. Why can I not edit the image size in UMG? There’s like every other setting except the most obvious one… :frowning:

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Probably because the feature you need has not been put yet into the engine. There needs to be a flag of some kind to allow the scrollbox to rescale the image, or not to when putting more things into it.

No chance of getting this functionality in-editor soon? Seems like quite an oversight.

Its not very hard with custom slider. Hide native scroll box slider, create new one, place it on same canvas as ScrollBox we want to scroll. Create event ‘on value change’ and bind slider value, as on pictures. Wish it was that easy from beginning =)

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I’m looking for same feature. This is not available on UE 5.0.3