BLT is an extension to the Tk toolkit, adding new widgets, geometry managers, and miscellaneous commands. It does not require any patching of the Tcl or Tk source files.

The latest release BLT 2.4u.tar.gz works with Tk versions 4.1, 4.2, 8.0, 8.1, 8.2, and 8.3.

Binary releases are available for Windows 95/98/NT. Please note that you can install only for 8.0, 8.1, 8.2, or 8.3 (choose one).


Tutorial slides are available as PDF files. Both files contain the same slides, just in different page layouts: one is one-per-page, the other is two-per-page.

slides.pdf contains one slide per page.
handouts.pdf contains two slides per page.

The BLT library adds the following commands to Tk:

table A table-based geometry manager for Tk. You specify the widget layout as row and column positions in the table. Has many options for constraining window resizing.
graph A X-Y graph widget. Plots two-variable data. Supports two sets of X and Y axes, inverted axes, custom axis layout.
barchart A barchart widget. Plots two-variable data using bars. Supports two sets of X and Y axes, inverted axes, custom axis layout.
vector Creates a vector of floating point values. The vector's components can be manipulated in three ways: through a Tcl array variable, a Tcl command, or the C API.
spline Computes a spline fitting a set of data points (x and y vectors) and produces a vector of the interpolated images (y-coordinates) at a given set of x-coordinates.
busy For handling user-interaction when the application is "busy". Manages an invisible "busy" window which prevents further user device (keyboard, mouse, button, etc.) interactions. Also provides a different cursor which supersedes application cursors.
bgexec Like Tcl's "exec ... &", but collects the output, error, and status of the detached UNIX subprocesses. Sets a Tcl variable upon completion. Can be used with "tkwait variable" to handle expose events, etc. while waiting for subprocesses to finish.
drag&drop Command which adds drag-n-drop capabilities to Tk. It provides "send"-style communication between drag-drop sources and targets. The result is a much more powerful drag-and-drop mechanism than is available with OpenLook or Motif.
htext A simple hypertext widget. Allows text and Tk widgets to be combined in a scroll-able text window. Any Tk widget can be embedded and used to form hyper-links. Other options allow for selections and text searches.
bitmap Command for creating and manipulating bitmaps from Tcl. Lets you read and write bitmaps from Tcl. Can also define X bitmaps and create bitmaps from text strings. Other options let you rotate and scale bitmaps.
winop Low-level Xlib calls let you raise, lower, map, or, unmap any window.
watch Lets you specify Tcl procedures to be run before and/or after every Tcl command. May be used for logging, tracing, profiling, or debugging or Tcl code.
bltdebug Prints out each Tcl command before it's executed.

For more information refer to the BLT 2.4u Readme file