I want the textbox to accept only numeric input

[TIMAI2]

Alternatively you can use Taifun's Textbox extension which has event listeners that you can use to control input.

Or you could build your own numeric keyboard with buttons (and hide the soft keyboard with an extension) which would limit data entry...

[SOLVED] Extension Suggestion: Hide System Keyboard

The regular 'call TextBox HideKeyboard' allows the system keyboard to pop-up again if the Text Box text is tapped and selected for editing. If the App has it's own bespoke Keyboard, the system keyboard needs to be hidden until the App code allows it to again be triggered by event.