Problem: when you select order to fill in orderbook it shouldn't be possible to select base coin amount more than selected order max. amount
For example I select order in orderbook with max amount 1 DEX:

But after selection for KMD amount selected max. and for DEX amount of my KMD multiplied on rate of the order I've selected:

You can try to select order in mobile orderbook and issue might became more clear than my explanation. Keep in mind that in DEX we fill concrete order.