In Estate of Markham (1941) 46 Cal. App. 2d 307, a beneficiary challenged a will on grounds including lack of mental capacity and undue influence. The Court of Appeal held: "We cannot conceive of a more outright and direct attack upon the validity of the will, or a more positive effort, in violation of the forfeiture clause therein, to 'set aside the probate of this will, impair, invalidate, or set aside its provisions, or to have the same or any part thereof, or any devise or devises or trusts herein limited declared void or diminished,' or to 'defeat or change any part of the testamentary plan' or endeavor 'to secure or take any part of my estate in any manner other than through or under this will,' any one of which attempts would bring appellant within the purview of the disinheriting clause." ( Id. at p. 316.)