You could create 2 more widget properties in the widget xml file where you define the min- and maxlength:
<property key="myInteger" type="integer" defaultValue="1000">
<caption>My integer</caption>
<description>My integer setting</description>
</property>
And then set those values as the min and max length properties of your input field:
<input type="number" id="this.props.myAttribute" name="this.props.myAttribute" min=”this.props.myMinInteger” max = this.props.myMaxInteger>
I don't want to control the range of input box, but I want to control the range of configuration information. As shown in the picture ([decimal precision] property of Mendix’s TextBox control panel).