Created attachment 99586 [details] Patch to correct behaviour When a select has only a few items the scrollbar is rendering larger then the control. For select controls with a large amount of items this is not an issue. Furthermore e.g. a scrolling div with a small amount of items does not exhibit the same problem. It seems that this is because the function wxRenderer_DrawScrollbar expects the current, max and step paramaters as pixel values but that in the case of Select objects the ScrollBar object instead uses "item" units internally e.g. a step of 1 item instead of 25 pixels, a maximum of 19 items instead of 300 pixels. These "item" values are passed into wxRenderer_DrawScrollbar as is which then confuses it. Instead these values should be converted into pixels before being passed to wxRenderer_DrawScrollbar. I am attaching a patch which corrects this behaviour, as well as a small snippet of HTML to reproduce the problem.
Created attachment 99587 [details] testcase
Wx port is gone. So closing this as "RESOLVED WONTFIX".