disable rescan-lookahead field if data source is third_party_explorer

static/admin/css/style.css

@@ -27,6 +27,12 @@ input[type="checkbox"]{
 	-webkit-transform: scale(1.3);
 }
 
+input:disabled, select:disabled {
+  border: 1px solid #8f8f8f;
+  color: #8f8f8f;
+  background-color: #3a3d3f;
+}
+
 a, a:visited {
 	color: #a1a1a1;
 }

static/admin/dmt/xpubs-tools/xpubs-tools.js

@@ -27,6 +27,10 @@ const screenXpubsToolsScript = {
   },
 
   preparePage: function() {
+    // Disable custom lookahead if data source is a third party explorer
+    const disableLookahead = sessionStorage.getItem('indexerType') == 'third_party_explorer'
+    $('#rescan-lookahead').prop('disabled', disableLookahead)
+
     this.hideRescanForm()
     this.hideDeletionForm()
     this.showSearchForm()