I know you have special tag structure so that you can implement certain features.  However, for UI elements like the drop-down, numeric input and date-picker, it would be really great to use (or have an alternative control to us) native html elements and data- attributes that are easily recognized by mobile devices and newer, desktop browsers.  For example, for the drop-down, it would be great for it to render a select so that when received by a mobile device, the native option selector can take over.  I am posting this in the Web controls for those of us creating responsive apps where the input surrounded by spans doesn't really work out very well when the page is rendered on a mobile browser.  I realize that are trade-offs so maybe instead of completely disregarding the current controls, maybe another, pure control, or some configuration option to the current controls would be preferable. That way, the developer could decide what was more important - the UI enhanced feature or compatibility with device.