Hi, 

We have some multiselect controls which can have a large number of values, and selected values. This causes an issue where the height becomes unreasonably large compared to other controls. 

For a typical example of the issue, see here: Multiselect height issue | Kendo UI Dojo

As can also be seen in the provided example, setting max-height with an overflow isn't a viable solution as then it becomes very difficult to see what has been selected - the vertical scroll is much too quick (at least it is using my mouse which has discrete scroll values). Also, there are both dropdown buttons and scroll buttons which is ugly and confusing for end users.

Our suggestion to resolve this would be to add an option for a "single line mode" so that functionality is not broken for other clients. When using this mode, all the items will be kept in a line. In the event of an overflow, then you could either a) cut off the items with an ellipsis "..." or b) enable horizontal scrolling (ideally without a visible scrollbar). 

See this example in the DevExpress controls for an example of horizontal scrolling in "Single line mode".
JavaScript/jQuery Tag Box - Overview | jQuery/JS Example
You can see that when all the items are selected, the height is kept consistent. It is still reasonably easy to read as you can easily scroll along.
Something similar to this solution would be ideal for us.