How to monitor applications being open or launch in linux/tcl/python?

Question

I am trying to build a panel application, alike avant window navigator or ubuntu unity.

My question is once I build the panel with the predifined applications, how I can add items to the panel when applications are open or launch?

Here is my source code in tcl:

package require Tk

set items {xterm gvim firefox}
wm withdraw .
toplevel .panel
wm attributes .panel -topmost 1 ; # on top
bind .panel <Escape> {exit}
wm geometry .panel +0+0
wm overrideredirect .panel yes ; # remove window decorations

set counter 0
foreach item $items {
    incr counter
    set separator " "
    label .panel.$counter -text "$item$separator" -bg black -fg white \
    -font {-family "Fixedsys Excelsior 3.01" -size 12}
    grid .panel.$counter -column $counter -row 0
}

Is there any terminal, tcl or python command that can achieve this?

Appreciate any insights. Thank you in advance.

Answer 1

If the send command is turned on (which depends on all sorts of factors related to the security of your display) you can just tell it to listen on a “well-known name” and then have another little app use send to dispatch a script to evaluate.

In the panel, listen on a “good” name:

package require Tk
tk appname MyExcellentPanel
proc registerItem args {
   # How to do the registration of things here
}

In the helper script:

#!/usr/bin/env wish
package require Tk
wm withdraw .                               ;  # IMPORTANT! Don't show a GUI here
send MyExcellentPanel registerItem $argv    ;  # The magic command
exit                                        ;  # IMPORTANT! Exit now

Now you can use that little script from a shell script or wherever to send an instruction to the panel to register something. It's as easy as that.

---

If the send command isn't present, try the comm package in Tcllib, with comm::comm send as the approximate equivalent of send. However, there's nothing exactly the same as tk appname as there's no portable way to do a registry of port mappings (comm uses local TCP channels) so you need to find a way to communicate that information (a file in a well-known place?). Alas, I'm not very experienced with it so I can't really advise in detail.