It turns out that multi-select dropdown listboxes, when clicked open, are limited to 5 lines - see below code in ibirls3.js around lines 10120-10130:

	inputCtrl.onclick = function(e)
	{
		...
		if (object.isMultiSelectCombobox)
		{
			var ctrl1 = object.getInputControl();
			if (ctrl1)
			{
				...
				ctrl1.size = valuesPop.length < 5 ? valuesPop.length : 5;

What's the reason for this peculiar limitation?

A multiselect dropdown is not a native HTML control. It is homemade. When it opens, you scroll to see all the values. The number of values visible at one time needs a size, so 5 lines is the size.

Well yes, that's what the code already told me. I didn't quote that for nothing.
The question is: why is it limited to a maximum of 5 visible items?
Why not 10 or 15 or something that we can decide?

Our end-users experience this limitation as inconvenient, but there's nothing we can do to increase it except by modifying the code responsible for the limitation. We can't use these multiselect dropdowns as they are.

It is the initial value when created. Can be changed at any time by just extending the box...

Those aren't multi-select dropdown lists. What you're showing are called listboxes.

The default for Listbox is 3, we just expand the box, works for us.
In 7.7.03 HTML Composer, when selecting Drop Down List, and, converting to Multiple, yes, it only displays 5, AND, actually, seems to convert to a list box. When it is a singular select, then, it is a drop down list. That is why we use the List Box concept for Multiple...

You could always ask Mr. David Glick to have IBI increase the size via a NFR...

It's basically a design-flaw then. Why would that require an NFR? That doesn't make sense.

Thanks Tom.

Wep,

That would be the thing to do. Open a new feature request for it to be configurable.