VTML files are source code files of the Visual Tool Markup Language (VTML). The Macromedia (now Adobe) VTML was used to extend the ColdFusion Studio and Dreamweaver development environment (with HomeSite +).
The VTML language can be used to create tag-specific dialog boxes and other UI elements that can be used to generate code fragments specified after user input.
An alternative and more common ending is vtm.
In the Dreamweaver folder under 'configurationTagLibraries' you can find VTML files for different purposes and languages (eg HTML, CSS, ASP.Net). These can be changed in Dreamweaver via 'Edit-> Tag Libraries' and used via the 'Insert-> Tag' menu.
Most often resolving problems with opening VTML files is very simple. Just install an appropriate program that supports such files. All of the listed programs support VTML files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of VTML files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate VTML files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Adobe Dreamweaver applications is not on the list, select "Browse" option in order to manually locate the directory where Adobe Dreamweaver has been installed.
Sometimes problems with opening VTML files may not lie with the application itself, but can arise due to other causes, such as: