After trying to make use of the javascript function dE() in the ACP, I discovered that it is outdated and will not correctly detect the visibility of the specified element correctly.
In the ACP, the function dE is defined as such:

/**

* Set display of page element

* s[-1,0,1] = hide,toggle display,show

*/

function dE(n, s, type)

{

	if (!type)

	{

		type = 'block';

	}

	var e = document.getElementById(n);

	if (!s)

	{

		s = (e.style.display == '') ? -1 : 1;

	}

	e.style.display = (s == 1) ? type : 'none';

}

In proSilver, the dE function is defined like so:

/**

* Set display of page element

* s[-1,0,1] = hide,toggle display,show

*/

function dE(n, s)

{

	var e = document.getElementById(n);

	if (!s)

	{

		s = (e.style.display == '' || e.style.display == 'block') ? -1 : 1;

	}

	e.style.display = (s == 1) ? 'block' : 'none';

}

The main difference between the function declarations is that of this snippet:

 || e.style.display == 'block'

Adding this into the ACP variant of the function corrected the problem for me.

At the moment, I am about to make a quick patch via git and submit a pull request, I'll reply back to this bug when I am done.