Qt is a cross platform ( Windows, Mac OS and Linux) C++ framework application and objects library.
This clever and elegant object oriented development tool initially developed by Trolltech, a norvegian company, successively acquired by Nokia, is now a property of Digia.
From the programming side it insulates the programmer from the operative system in use, despite this the applications created with Qt are 100% native. For this reason it is the perfect tool to handle cross-platform projects, but it is a convenient development environment also if you decide to deploy only for one single operative system.
Qt is also the perfect tools for custom applications since it allows to reduce the development time and consequently also the development costs, still keeping a very high quality standard.
I have developed some digital signage solutions using Qt with the Linux os and also a cross-platform (Windows and MacOS) graphic application supporting a road design application.
I had a good exposure to this programming tool so I could help you to create a cost effective cross-platform solution.