Blt is a library of useful extensions for the tcl language and the popular tk graphical toolkit. it adds a vector and tree data type, background execution and some debugging tools to tcl, and provides several new widgets for tk, including graphs, bar-charts, trees, tabs, splines and hyper-links, as well as a new geometry manager, drag & drop support, and more.

this package contains the headers and libraries needed to extend or embed blt.