test

mon = peripheral.find("monitor")
local Xpos = 5
local Ypos = 5
local Xend = 30
local Yend = 8
local Yfill = 0

function fill()
mon.setBackgroundColor(colors.blue)
width = Xpos-Xend
heigth = Ypos-Yend
mon.setCursorPos(Xpos,Ypos)
while i <= width do
Yfill = Yfill + 1
if Yfill <= heigth then
for b = 1,width do
mon.write(" ")
end
i = 1
end
end