The error messages speak for themselves. In line 46/124, $t doesn't appear to be defined at all, and it looks like there's something similar causing the "Not a Tk Object" error.
My best guess is variable clash - removing all those requires was a *good* thing (but check out modules and the use statement sometime soon), but I reckon there are variables in the subs called $t somewhere that aren't localised...are you using strict & warnings? If not, do. They should be able to help you catch errors like this.