New
#1
You are showing a Lookup not a Balloon tip. Helps to know what program you are using that you did not state how you got that Lookup.
I got the lookup by hovering over text in an e-mail in Thunderbird. I'd like to stop them for all programs, since they make things a lot harder to read, especially when using magnifiers like Fatbits.
If you choose to read your Email in plain text instead of HTML, you will not get Lookups. Plain text e-mail - Thunderbird - MozillaZine Knowledge Base
Every program has its own way to not have the hover over look up. As spunk stated, read in Plain Text. It has to do with CSS in Thunderbird. Plenty of stuff out there for you to create a CSS sheet to make Thunderbird do what you want.
I use Postbox, so I do not get any of that stuff due to how the company that created Postbox from the Thunderbird code made a lot of changes.