<!-- drawing_c.lua -->
<!-- paste at script start -->
local brush_size = 4

<!-- paste between lines 21 and 22 -->
    button_1x = guiCreateButton(304,320,64,24,"0.5x",false,draw_window)
    button_2x = guiCreateButton(368,320,64,24,"1x",false,draw_window)
    button_3x = guiCreateButton(432,320,64,24,"2x",false,draw_window)
    addEventHandler("onClientGUIClick",button_1x,clickSize,false)
    addEventHandler("onClientGUIClick",button_2x,clickSize,false)
    addEventHandler("onClientGUIClick",button_3x,clickSize,false)

<!-- paste at end -->
function clickSize()
    if source == button_1x then
        brush_size = 2
    elseif source == button_2x then
        brush_size = 4
    elseif source == button_3x then
        brush_size = 8
    end
end