VoidUI.Frame is the moma of basically all VGUI elements. 98% of the time you will parent your element to this.
Derived methods, etc not listed on this page from DFrame.
PANEL:SetTitle(title)
PANEL:StayOnTop()
PANEL:PerformLayout(w, h)
PANEL:Think()
PANEL:Paint(w, h)
local mainframe = vgui.Create("VoidUI.Frame") -- The name of the panel we don't have to parent it.
mainframe:SSetSize(900, 500) -- Set the size to 900(width) x 500(height) pixels.
mainframe:Center() -- Centers the frame on the screen.
mainframe:SetTitle("VoidUI Frame") -- Set the title in the top to "VoidUI Frame".
mainframe:MakePopup() -- Makes your mouse be able to move around.