Virtual Keyboard Tools consists of a few classes and one tool which may be helpful in creating virtual keyboards with your own design.
All you have to do is to create two keyboard layout images (one with all keys pressed and another with released) using any graphics tools and create a keyboard layout document using VKB Layout Editor. Then you can use the VkbItem class for viewing and interacting with your virtual keyboard in your applications.
With the VkbItem class you can also setup keyboard layouts switching.
Depends on Qt 4.6.