Web browser will be the most popular GUI front-end in the future. A major portion of code should be written in Web server scripting (and compiling) language PHP+Zend compiler, HTML, DHTML and with little bit of JavaScript and Java-Applets on web-client side. It is recommended that you migrate all of your "legacy" Windows 95/NT applications to PHP + HTML + DHTML and Zend compiler. PHP is extremely powerful as it combines the power of Perl, Java, C++, Javascript into one single language and it runs on all OSes - unixes and Windows NT/95.
The best tools in the order of preference are -
Language choices in the order of preference are -
There are other tools available - PostgreSQL has Tcl/Tk interface library in the distribution called 'pgTcl'. There is a IDE (integrated development environment) for Tcl/Tk called SpecTcl.