How to add space between a list and vertical scrollbar?

[byorgey]

I am rendering a brick list and wanted to add a scrollbar. That worked fine, but the scrollbar was immediately next to the list items with no intervening space, which I thought looked bad. But since the viewport is actually created inside the renderListWithIndex function, it seems like I can't insert padding in between the rendered items and the viewport (without duplicating renderListWithIndex and making my own modified version). I was able to create some space by putting padding on the end of the rendered list items, but now the highlighting for the current list item extends all the way to the scrollbar (see the screenshot below), which I don't want. I just want a one-space-wide vertical blank strip in between the list items and the scrollbar.

Any ideas on how this might best be accomplished?

[jtdaugherty]

Right now, I think the approach you took is the only way: to add a bit of padding to the right side of each list element. The undesirable attribute behavior can probably be fixed with some clever attribute map changes, but that isn't how I'd like this to work. I'd like to think about this some more, but I'm leaning toward augmenting the library's scroll bar configuration API with a spacing setting to make this a first-class feature.

[jtdaugherty]

@byorgey I've pushed 324b5ad to master. Please check it out! You can see a working example of a modified scroll bar renderer in programs/ViewportScrollbarsDemo.hs. In your case it would be something like the following, provided you wanted to piggyback on the default renderer without repeating it:

addLeftSpacing :: VScrollbarRenderer n -> VScrollbarRenderer n
addLeftSpacing r =
    r { scrollbarWidthAllocation = 2
      , renderVScrollbar = hLimit 1 $ renderVScrollbar r
      , renderVScrollbarTrough = hLimit 1 $ renderVScrollbarTrough r
      }

and then

myWidget :: Widget n
myWidget =
    ...
    withVScrollBarRenderer (addLeftSpacing verticalScrollbarRenderer) $
    ....

That will automatically result in spacing on the left if your scroll bar orientation is on the right.

[jtdaugherty]

After discovering a wart in the API, I went a bit further and introduced some more changes in 6b7195c that should be easy to adjust for, but I wanted to call that out in case you pull master later and get both changes. I'll edit my example above to account for the change.

[byorgey]

I tried it out and it works great!

[jtdaugherty]

Okay, great. I'll make a release over the weekend.

[jtdaugherty]

The changes are now released in 1.10.