This is already fixed in SVN r5420 (1.1.x) and r5421 (trunk).

This still doesn't work (in 1.1.5)

seweso, if you have problems in setting an option in the interface (anyway, I'd still suggest storing it in the config_inc.php file), please detail what are you doing and what do you get.

For this purpose, it is preferred to use the mailing list mantisbt-help@lists.sourceforge.net or our forums http://www.mantisbt.org/forums.

It works just fine when you use it as jreese wrote.
The problem is that it is very selective:
array( a=>1, b=>2, c=>3, d=>4 )
is ok, but the following, very common ways to represent an array, are not.
array(
a=>1,
b=>2,
c=>3,
d=>4
)
or
array( a=>"1", b=>"2", c=>"3", d=>"4" )

I had a lot of trouble with this one because the easy way to introduce new entries is to copy the existing ones from the view and alter them (which doesn't work since quotation is not allowed, neither are line breaks)

Maybe adding some help right on the configuration admin screen would be a good idea

yeas, unfortunately, the strictness is a side effect of the fix for the security issue detailed in 0008976.

It would be nice to have an improved system for editing the configuration options, ideas are welcome on the mantisbt-devel mailing list.

I changed mine to the following which worked for me, sorry I don't use git so I can't make a patch for it, but can anyone see any reason why this isn't ok?

adm_config_set.php line 84

if ( preg_match('/array[\s]*\(([\s\S]*)\)/', $t_full_string, $t_match ) === 1 ) {
        // we have an array here
        $t_values = preg_split("/,[\s]+/", trim( $t_match[1] ) );
        foreach ( $t_values as $key => $value ) {
            $t_split = preg_split( "/[\s]*=>[\s]*/",  $value, 2 );
            if ( count( $t_split ) == 2 ) {
                // associative array
                $t_new_key = constant_replace( trim( $t_split[0] ) );
                $t_new_value = constant_replace( trim( $t_split[1] ) );
                $t_new_value = ereg_replace("'?([^\']+)'?,?", '\\1', $t_new_value);
                $t_value[ $t_new_key ] = $t_new_value;
            }

It allows me to cut & paste previous values and edit them, I haven't tested with all array types admittedly, but I haven't needed them at all so don't have time to do that sorry.

The last ereg_replace should have '"' included also perhaps but I think as long as one format works people can be happy enough with it.
\"?'?([^\"']+)\"?'?,?