Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
Can reproduce in 1.7.2 with "Splash Potion of Water Breathing", see another screenshot, maybe this is dependant on the number of characters in the original string.
This seems to be dependent on the width of the proportional characters, because the two 32 chars long strings behave diffrerent: Splash Potion of Water Breathing is cut off Splash Potion of Fire Resistance is not cut off
The limit of the textbox now matches the hard limit of item names, so things won't unexpectedly be truncated. The "garbage on the end" is just a textbox thing, when there's more than can fit on the screen immediately.
Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.