• VSCode Version: 1.5.0-insider
• OS Version: Windows 10

Steps to Reproduce:

1. Run await vscode.window.showInputBox({prompt: "cmd line", value: "set"})
2. the value set is highlighted/selected

Currently we can't put the cursor at the end of the default value when running showInputBox. In this case, users have to move the cursor manually if we want to keep the default value as prefix always.