VBScript allows replacing the text in the window, even from different scripts. Uses HTA, no temp files.
showmessage "Time is " & now
sub showmessage(text)
' source http://forum.script-coding.com/viewtopic.php?pid=75356#p75356
dim shellwnd, proc, wnd
on error resume next
for each shellwnd in createobject("Shell.Application").windows
set wnd = shellwnd.getproperty("messagewindow")
if err.number = 0 then
wnd.document.body.innerhtml = text
exit sub
end if
err.clear
next
do
set proc = createobject("WScript.Shell").exec("mshta ""about:<html><head><script>moveTo(-32000,-32000);</script><hta:application id=app border=dialog minimizebutton=no maximizebutton=no scroll=no showintaskbar=yes contextmenu=no selection=no innerborder=no /><object id='shellwindow' classid='clsid:8856F961-340A-11D0-A96B-00C04FD705A2'><param name=RegisterAsBrowser value=1></object><script>shellwindow.putproperty('messagewindow',document.parentWindow);</script></head></html>""")
do
if proc.status > 0 then exit do
for each shellwnd in createobject("Shell.Application").windows
set wnd = shellwnd.getproperty("messagewindow")
if err.number = 0 then
with wnd
.document.title = "Message"
.document.body.style.background = "buttonface"
.document.body.style.fontfamily = "verdana"
.document.body.style.fontsize = "0.7em"
.document.body.innerhtml = text
.resizeto 300, 150
.moveto 200, 200
end with
exit sub
end if
err.clear
next
loop
loop
end sub