Salesforce held TrailheaDX last week -- its first event just for software developers. The company previously relied on special sessions at events such as Dreamforce to educate developers, but its declared intention to train up to 100 million of them in its Lightning development environment dictated taking additional action. The numbers vary, but estimates of the number of professional developers working in the industry range from 100,000 to perhaps 20 million. Salesforce contends that anyone should be able to learn development skills.