The code would look something like that below. Basically I'm wondering if you scale the stage to the screen size, if there is a way to adjust the mouse X and Y coordinates to the new size -- the coordinates provided I've found that it's a bit offset the further toward bottom right you go from the pointermove event.
//Scale stage
var resolution_width = 1024
var resolution_height = 768
app.stage.scale.x = window.innerWidth / screen_width;
app.stage.scale.y = window.innerHeight / screen_height;
//Get mouse x and y on mouse move
app.stage.pointermove = moved;
function moved(e)
{
console.log([e.data.global.x,e.data.global.y]
}