1568511 - <select> dropdown closes unexpectedly

Status: RESOLVED DUPLICATE of bug 1440506

(Core :: Layout: Form Controls, defect)

Description

[cypherzero]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:68.0) Gecko/20100101 Firefox/68.0

Steps to reproduce:

I have included a minimal example.

HTML:

<div>
<select>
<option>This is an option</option>
<option>This is an option</option>
<option>This is an option</option>
<option>This is an option</option>
<option>This is an option</option>
<option>This is an option</option>
<option>This is an option</option>
<option>This is an option</option>
<option>This is an option</option>
<option>This is an option</option>
</select>
</div>

CSS:

div:hover::before
{
position: fixed;
top: 1em;
left: 20em;
height: 1em;
max-width: 20em;
overflow: hidden;
}

div:hover::before
{
content: "This is a message.";
animation: my_anim 2.5s linear 0s normal;
}

@keyframes my_anim
{
0%
{
max-width: 0;
}
100%
{
max-width: 1024px;
}
}

NOTES:

Ubuntu 18.04. Firefox 68.0.

Actual results:

The select dropdown randomly closes as you move the mouse over the elements, this appears to be affected by playing a CSS animation.

Expected results:

The select dropdown should stay open until you select an element or click elsewhere.