Other Tk Changes

Mouse Button Repeat Control

You can now configure how buttons, scales, scrollbars, and spinboxes respond when the user holds down a mouse button or key for that widget. The repeatDelay attribute specifies the number of milliseconds a button or key must be held down before it begins to auto-repeat, and the repeatInterval attribute determines the number of milliseconds between auto-repeats.

Better Support for Image Transparency

Tk 8.4 provides greater access to transparency information for photo images. Photo image object commands now support a transparency subcommand with get and set operations, which respectively get and set the transparency setting of individual pixels in the image. (TIP #14) Additionally, a new -compositingrule option to the copy subcommand allows you to specify how transparent pixels in the source image are combined with the destination image. (TIP #98)

Selecting Multiple Files with tk_getOpenFile

The tk_getOpenFile -multiple option allows a user to select multiple files to open, returning the files selected as a list.

Fixed-Width Button Support on Windows Systems

On Windows systems, the button width attribute now accepts a negative value to specify a minimum width, enabling better compliance with native Windows look-and-feel.

Easier Access to Clipboard Contents

A new clipboard get subcommand returns the contents of the clipboard — equivalent to selection get -selection CLIPBOARD.

Determining if an Image is Used

The image inuse command returns whether or not a specified image is in use by any widget.

New Events and Substitutions for Window Managers

To enable writing Tk-based window managers, Tk 8.4 added support for five new event types: <CirculateRequest>, <Create>, <MapRequest>, <ResizeRequest>, and <ConfigureRequest>. The %i and %P event substitutions were also added. (TIP #47)

Caret Management for Improved XIM/IME Support

A new tk caret command sets and queries the caret location for the display of the specified Tk window. The caret is the per-display cursor location used for indicating global focus (for example, to comply with Microsoft Accessibility guidelines), as well as for location of the over-the-spot XIM (X Input Methods) or Windows IME windows. (TIP #96)

New bell Option to Prevent Resetting Screen Savers

The bell command has the side effect of resetting the screen saver for the screen, which usually makes the screen visible again. The new -nice option prevents the bell command from resetting the screen saver.

Generating Postscript for Embedded Widgets

The Tk 8.4.1 patch release added the ability on Windows for the canvas to generate Postscript for embedded widgets currently displayed on the screen (that is, displayed within the canvas's viewport and not obscured by other windows). This capability was added concurrently with the 8.3.5 patch release.