I tried running the server.tcl program, but it presented a couple of problems.

Firs tof all: I checked out the source code from the repository today.

This is what I did:
I clicked on, respectively, the Hello, World demo. THis led to an internal error.

I clicked on the demo.tcl script - nothing appeared

I clicked on the sketch.tcl script - a simple but elegant drawing window appeared, but sketching did not work.

I copy the output from the server.tcl program below:

Started wtk demo on http://localhost:9001
URL: /
URL: /
URL: /src.html
URL: /sapui5.html
bgerror: Error processing handler for /sapui5.html:
couldn't open "sapui5.html": no such file or directory
    while executing
"open $fn"
    (procedure "filecontents" line 1)
    invoked from within
"filecontents $url"
    (procedure "webhandler" line 21)
    invoked from within
"webhandler handle sock412"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 $Httpd(responsehandler) handle $sock"
couldn't open "sapui5.html": no such file or directory
    while executing
"open $fn"
    (procedure "filecontents" line 1)
    invoked from within
"filecontents $url"
    (procedure "webhandler" line 21)
    invoked from within
"webhandler handle sock412"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 $Httpd(responsehandler) handle $sock"
URL: /demo.tcl
::wtk::widgets(.) = id obj0
URL: /lib/jquery.min.js
URL: /widgets/wtk.js
URL: /resources/sap-ui-core.js
bgerror: Error processing handler for /resources/sap-ui-core.js:
couldn't open "resources/sap-ui-core.js": no such file or directory
    while executing
"open $fn"
    (procedure "filecontents" line 1)
    invoked from within
"filecontents $url"
    (procedure "webhandler" line 12)
    invoked from within
"webhandler handle sock416"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 $Httpd(responsehandler) handle $sock"
couldn't open "resources/sap-ui-core.js": no such file or directory
    while executing
"open $fn"
    (procedure "filecontents" line 1)
    invoked from within
"filecontents $url"
    (procedure "webhandler" line 12)
    invoked from within
"webhandler handle sock416"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 $Httpd(responsehandler) handle $sock"
URL: /resources/sap-ui-core.js
bgerror: Error processing handler for /resources/sap-ui-core.js:
couldn't open "resources/sap-ui-core.js": no such file or directory
    while executing
"open $fn"
    (procedure "filecontents" line 1)
    invoked from within
"filecontents $url"
    (procedure "webhandler" line 12)
    invoked from within
"webhandler handle sock404"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 $Httpd(responsehandler) handle $sock"
couldn't open "resources/sap-ui-core.js": no such file or directory
    while executing
"open $fn"
    (procedure "filecontents" line 1)
    invoked from within
"filecontents $url"
    (procedure "webhandler" line 12)
    invoked from within
"webhandler handle sock404"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 $Httpd(responsehandler) handle $sock"
URL: /wsctrl
Socket sock416 upgraded to WebSocket for sessionid 1384162461589
URL: /sketch.tcl
URL: /lib/jquery.min.js
URL: /widgets/wtk.js
URL: /resources/sap-ui-core.js
bgerror: Error processing handler for /resources/sap-ui-core.js:
couldn't open "resources/sap-ui-core.js": no such file or directory
    while executing
"open $fn"
    (procedure "filecontents" line 1)
    invoked from within
"filecontents $url"
    (procedure "webhandler" line 12)
    invoked from within
"webhandler handle sock428"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 $Httpd(responsehandler) handle $sock"
couldn't open "resources/sap-ui-core.js": no such file or directory
    while executing
"open $fn"
    (procedure "filecontents" line 1)
    invoked from within
"filecontents $url"
    (procedure "webhandler" line 12)
    invoked from within
"webhandler handle sock428"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 $Httpd(responsehandler) handle $sock"
URL: /resources/sap-ui-core.js
bgerror: Error processing handler for /resources/sap-ui-core.js:
couldn't open "resources/sap-ui-core.js": no such file or directory
    while executing
"open $fn"
    (procedure "filecontents" line 1)
    invoked from within
"filecontents $url"
    (procedure "webhandler" line 12)
    invoked from within
"webhandler handle sock384"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 $Httpd(responsehandler) handle $sock"
couldn't open "resources/sap-ui-core.js": no such file or directory
    while executing
"open $fn"
    (procedure "filecontents" line 1)
    invoked from within
"filecontents $url"
    (procedure "webhandler" line 12)
    invoked from within
"webhandler handle sock384"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 $Httpd(responsehandler) handle $sock"
URL: /wsctrl
Socket sock428 upgraded to WebSocket for sessionid 1384162461589
bgerror: invalid command name "<<<<<<<"
invalid command name "<<<<<<<"
    while executing
"<<<<<<< BEGIN MERGE CONFLICT: local copy shown first <<<<<<<<<<<<<<<"
    (procedure "::wtk::fromclient" line 5)
    invoked from within
"::wtk::fromclient {EVENT obj1 mousemove 67 154 0 }"
    invoked from within
"[dict get $::session($sessionid) interp] eval ::wtk::fromclient [list $cmd]"
    (procedure "ws_receive" line 29)
    invoked from within
"ws_receive junk sock428"

I repaired the code that was mangled by the merge conflict. 

The sketch demo does work - it was a bit slow in reacting, but I can only draw lines, not rectangles etc. it seems.