Tooltip regex matches gchq#279

Tooltip shows offset and matched groups

src/core/operations/RegularExpression.mjs

@@ -227,6 +227,7 @@ function regexList (input, regex, displayTotal, matches, captureGroups) {
  */
 function regexHighlight (input, regex, displayTotal) {
     let output = "",
+		title = "",
         m,
         hl = 1,
         i = 0,
@@ -241,8 +242,16 @@ function regexHighlight (input, regex, displayTotal) {
         // Add up to match
         output += Utils.escapeHtml(input.slice(i, m.index));
 
+		title = "Offset: " + m.index + "
";
+		if (m.length > 1) {
+			title += "Groups:
";
+			for ( let n = 1; n < m.length; ++n) {
+				title += n + ": " + m[n] + "&#10;";
+			}
+		}
+
         // Add match with highlighting
-        output += "<span class='hl"+hl+"'>" + Utils.escapeHtml(m[0]) + "</span>";
+        output += "<span class='hl"+hl+"' title='"+title+"'>" + Utils.escapeHtml(m[0]) + "</span>";
 
         // Switch highlight
         hl = hl === 1 ? 2 : 1;