Grid Header input, then Auto fill every row

 

Step-1:
=====

Create a Grid Region and set query.

Select My column. (LEAD_MIN_DAY) 

Heading: <div style="text-align:center;"> Lead Min Day <br> <input type="number"        id="customHeaderInput_1"        style="width:70px;               text-align:center;               color:red;               border:2px solid red;"> </div>

Step-2:
=====

Create a dynamic Action.

Name: LEAD_MIN_DAY

Event: Change

Selection Type: jQuery Selector

jQuery Selector: #customHeaderInput_1

Action: Execute JavaScript Code

code:

var model = apex.region("ITEM_GRID").widget().interactiveGrid("getViews", "grid").model; // Grid Static ID

var newValue_1 = $(this.triggeringElement).val();

model.forEach(function(record) {

    model.setValue(record, "LEAD_MIN_DAY", newValue_1); // Updates every record in the model

});