Several wm subcommands were added to provide additional interaction with the window manager and control over toplevel windows:

wm attributes returns or sets platform-specific attributes associated with a window. (TIP #95)
wm stackorder returns information about the stacking order of an application's toplevel windows. (TIP #74)
wm iconbitmap accepts a new -default option on Windows platforms for designating a default icon bitmap for all of an application's toplevel windows. (TIP #8)
tk windowingsystem returns the current Tk windowing system, one of x11 (X11-based), win32 (MS Windows), classic (Mac OS Classic), or aqua (Mac OS X Aqua). (TIP #108)