The playable world stops at the start of bottom ui, in warcraft 3 versions before V1.32.
When your version has some frame api one can extent the world frame. Or maybe there is some 3rd party launcher that does it in your version.
In V1.31.1 this line would do it:
call BlzFrameSetAllPoints(BlzGetOriginFrame(ORIGIN_FRAME_WORLD_FRAME, 0), BlzGetOriginFrame(ORIGIN_FRAME_GAME_UI, 0))