Make the label weight window non-modal

[wayfaringrob]

Right now when modifying label weights, you must close the weights window to interact with your map. Setting label weights is rarely a linear process and requires a LOT of back and forth testing with different settings, and the apply button/moving the window out of the way only goes so far. Sometimes you want to move and zoom your map around to look at different areas, or change other settings while also tinkering with the label weights. This workflow would be made much more efficient if the label weights box were NOT modal as it currently is.