[fix] datepicker and autosuggest layering (fixes frappe/erpnext#3433)

frappe/public/css/desk.css

@@ -394,10 +394,18 @@ ul.linked-with-list li {
 .modal-title {
   margin-top: 5px;
 }
-.modal .form-control {
+.form-control {
   position: relative;
+}
+.link-field.ui-front {
+  z-index: inherit;
+}
+.modal .hasDatepicker {
   z-index: 1140;
 }
+.modal .link-field .ui-autocomplete {
+  z-index: 1141;
+}
 .form-group {
   margin-bottom: 7px;
 }

frappe/public/js/frappe/form/control.js

@@ -28,7 +28,6 @@ frappe.ui.form.Control = Class.extend({
 	make: function() {
 		this.make_wrapper();
 		this.$wrapper
-			.addClass("ui-front")
 			.attr("data-fieldtype", this.df.fieldtype)
 			.attr("data-fieldname", this.df.fieldname);
 		this.wrapper = this.$wrapper.get(0);
@@ -934,7 +933,7 @@ frappe.ui.form.ControlSelect = frappe.ui.form.ControlData.extend({
 frappe.ui.form.ControlLink = frappe.ui.form.ControlData.extend({
 	make_input: function() {
 		var me = this;
-		$('<div class="link-field" style="position: relative;">\
+		$('<div class="link-field ui-front" style="position: relative;">\
 			<input type="text" class="input-with-feedback form-control">\
 			<span class="link-btn">\
 				<a class="btn-open no-decoration" title="' + __("Open Link") + '">\

frappe/public/less/desk.less

@@ -225,12 +225,23 @@ ul.linked-with-list li {
 }
 
 // fixes datepicker z-index issue
-// datepicker takes zindex of input + 1 when input's position is relative
-.modal .form-control {
+.form-control {
 	position: relative;
+}
+
+.link-field.ui-front {
+	z-index: inherit;
+}
+
+.modal .hasDatepicker {
 	z-index: 1140;
 }
 
+.modal .link-field .ui-autocomplete {
+	// so that it appears over the datepicker field
+	z-index: 1141;
+}
+
 .form-group {
 	margin-bottom: 7px;
 }