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, ...]