There really needs to be a are you sure question if you click on the plus mark next to the stamina, as i did accidentally last night. I havnt done much of anything in a few days due to current issues on my account so i had full stamina, went to check what the plus sign was and bam 20 gems gone for stamina that i didnt even need or could even hold. Really needs to be addressed IMO, and im sure at this point im out my gems.