This is somewhat doable in UDL, currently. From my comment in the Stupid Tricks thread: Dynamic Lighting "Windows" (UDL only) There are 3 methods to do create them: (Plus user) Use the Freehand Drawing Tool and draw a back-and-forth line,starting and ending the drawing on the same spot, on the Map or Token Layer ,
and then move it to the DL layer. You can't use the free hand drawing
tool on the DL layer, and need to draw it on another layer. The
starting/ending spots will create a small dot that isnt see through, but
even with a short window you should get more than 90% of your section
like you want. (Pro user, API) TheAaron has a dedicated API for it called UDLWindows (Pro user, API) Use Scott C's DoorKnocker API version DoorKnocker1x211.js to convert regular DL lines into "windows".