Multi-line editbox

[MaLarsson]

What I want is a 300x300 px big editbox in which multiple lines can be writen, this is the code I have:

local editBoxSpells = CreateFrame("EditBox", "DoTrackerEditBoxSpells", menu, "InputBoxTemplate")
editBoxSpells:SetMultiLine(true)
editBoxSpells:SetSize(300, 300)
editBoxSpells:SetPoint("TOPLEFT", 300, -107)
editBoxSpells:SetAutoFocus(false)
editBoxSpells:SetText("test")
editBoxSpells:SetCursorPosition(0)
editBoxSpells:SetFont("Fonts\\FRIZQT__.TTF", 10)
editBoxSpells:SetJustifyH("LEFT")
editBoxSpells:SetJustifyV("CENTER")

The problem I have is this:


The background and border of the editbox does not fill up the entire 300x300 px big editbox.