See also "[Using Tcl to write WWW client side applications within the WWW browser]",
"[BrowseX]", "[Invoking browsers]", ...












----
I'll explain this at some point:
    package require tcom
    wm overrideredirect . on
    pack [canvas .c -background blue -height 20 -width 20]

    proc paste_on_top_IE toplevel {
        set application [::tcom::ref getactiveobject \
                             InternetExplorer.Application]
        wm geometry . +[$application Left]+[$application Top]
        raise .
        update idletasks
        after 300 [list paste_on_top_IE $toplevel]
    }

    paste_on_top_IE .


Notice the use made of [tcom].

























[[Eventually explain Browser Helper Objects, XUL, toolbar SDK, ...]]