mgraphics set_line_width madness

For some reason, set_line_width isn't working in jsui/mgraphics. I'm updating the line width based on the mouse position. If I post the value (or call get_line_width) to the Max window, I see values I would expect to see (example :jsui: 21.70 22.35 23.15 23.50 23.70 23.80 24.20 ), but all I get are lines 1 pixel thick (see attached image for demo).

The code is below. Any help would be appreciated. Javascript is still a foreign beast to me.

autowatch =1;
var width = 550;
var height = 550;
var mouseX = 0;
var mouseY = 0;

mgraphics.init();
mgraphics.relative_coords = 0;

function paint(){
    mgraphics.set_source_rgba(1, 1, 1, 1);
    mgraphics.paint();
    
    var circleRes = 2+ (80 - 2)*((mouseY -0)/ (height-0));
    var rad = mouseX-width/2 + .5;
    var angle = (Math.PI*2)/circleRes;
    var wide = mouseY/20;
        
    mgraphics.translate(width/2, height/2);
    mgraphics.set_source_rgb(0,0, 0,0);    
    
    mgraphics.set_line_cap("square");
    mgraphics.set_line_width(wide);

    for(var i=0;i