WebListBox: visible row height resize on load

When I load my WebListBox with data, the rows briefly are justified to fill the entire height, then a few milliseconds later, they snap back into being the expected height, as shown in this video:

WebListBox Row Height Video

Is there any way to prevent this? I’ve tried hiding / showing the listbox, but this doesn’t help, I still see the row height resizing.

[Edit to add: seeing this with 2021 R3, but I don’t think this is a new behavior]

Same behavior any browser?

Good question: yes, I am seeing it in both Safari and Chrome.


  1. If I make the browser window very short (so there are more listbox rows than can be displayed at once in the listbox ) then I don’t see the problem.
  2. However, if I then stretch the browser window, the rows jump back to filling the listbox height again, and I can’t get them to go back to normal.
  3. And, the behavior in #2 only happens if I start with a small window. If I start with a large window, make it small, then make it big again, it doesn’t happen.
  4. [Edit to add]: actually, sometimes I do see the behavior in #2, even when starting with a large window. It’s somewhat random.

It looks like it’s happening when the listbox says “I need to load another row”.

I’ll see if I can put together a demo project.

1 Like

Very easy to reproduce:

Tested in Vivaldi - confirm the row size effect.
Now, I was able to eliminate that effect:
add to Shown event of Listbox:

Var s As New WebStyle
s.Value("height") = "50px"
Style =s

That will break the bottom lock, no?

Just tested with less and multiple rows - no issues.

Here is the issue, at least on my mac with Chrome, Safari and Firefox.

Original code, lock bottom correct:

With your code, lock bottom wrong:

After experimenting some more (I already added information to case 66621), I have a “fix” but it needs to be executed after the listbox Shown event. It looks like JavaScript style changes in the shown event is replaced by Xojo, maybe needs to evaluate Shown changes to create the final listbox (I don’t know).

Here is the proof of the concept, see how the height is wrong when the webpage is resized and correct after applying the fix:
wlhfix.2021-11-20 09_00_51

Basically what the Fix does is:

  • set style=“height: 48px;” for each row
  • remove “line-height” for the buffer row

I don’t know if Greg thinks this is easier to implement or to update the “line-height” for the buffer row when the webpage is resized (as I mentioned in the case).

For case 66622 it looks like the WebListbox first is drawn without the buffer row, then drawn again with the buffer row. Maybe sending all rows with style height and draw the listbox with a buffer row without line-height will make sense to fix that problem too. But I don’t know exactly how the WebListbox works.

I hope this helps.