saas-one/frontend/operation-web/ext/classic/theme-graphite/overrides/form/field/File.js

Ext.define('Ext.theme.graphite.form.field.File', {
    override: 'Ext.form.field.File',
    _pressedCls: 'x-form-field-file-buttononly',
    beforeRender: function() {
        this.callParent();
        if (this.buttonOnly) {
            this.addCls(this._pressedCls);
        }
    }
});