Hello, when initial gui_window_position_frame is called the first time, x1/y1 is -1. I guess this is because I haven't called browser_window_reformat after openening the frame ( browser_window_reformat is the correct function for letting netsurf know the size of an window? Is there any better function to call after resize? ). I can't call browser_window_reformat right after creation of an frame or window, because that throws an assert about an invalid state for browser_window_reformat... How Do I tell NetSurf the size of the window/frame after creating an frame? Or should I handle the -1 differently? If I resize the window, I call browser_window_reformat, which also results in gui_window_position_frame, but this time x1,y1 is set correct like I reported it to browser_window_reformat. Maybe there is an callback which is called after the page rendering is complete? So that I could call browser_window_reformat then? Thanks for reading & Greets, Ole