ANY CARD with x in the cost should ALSO have a button to click that says "MAX" ! so i dont have to waste time counting all my mana!

this is so OBVIOUSLY needed.. another thing that should have been added long long ago.. you guys used to have a button for plus 1 minus 1, then you geniuses decided to add a plus 5 minus 5, but you couldnt think of this MAXIMUM button ? for example yet again, heliods intervention, it asks what you want to do, you click gain life, it asks WHO to gain life, OMG really, ok me of course duh, it asks how much life do i want to gain.. what if i have like 17 lands out there, but of course, the game wont tell you that you have 17 lands, you have to use your eyeballs to count them, so what if i count them like 3 times and waste tons of time, and still manage to count wrong, so i count 18 lands, so i type in x=16 by clicking plus 5plus5 plus 5 plus 1 ok 16 .. but OOPS oh now i counted wrong i only have 17 lands so x can only be 15 since it costs 2 mana to cast it, so now the spell just cancels itself angrily and i have to start all over again.. oh no wait my timers are gone my turns over and oh no i just lost the game!! but what if there was a smarter way, like having a "MAX" button next to the "+5" button that i could click to tell the game to just use all the maximum available mana for x!?! wouldnt that be just ingenious? ?how convenient.. would that be.. maybe then i could stop running out of time in the middle of casting a card and thus losing over that..