Allow to reduce the override-time on override-page

override.html

@@ -47,6 +47,13 @@
 				<p>Override activated. Blocking will be suspended until <strong><span id="alertOverrideEndTime"></span></strong>.</p>
 				<p id="alertOverrideNoSets"><strong>Note:</strong> Override will have no effect because you have not selected<br>"Allow temporary override for these sites" for any block sets.</p>
 				<p id="alertOverrideSets" style="display: none;">Override will be applied to sites in: <span id="alertOverrideSetList"></span></p>
+				<br>
+				<div id="updateOverride">
+					<div><b>Change Duration</b></div>
+					<div id="slider" style="margin-top:1em;margin-right: 6em;">
+						<div id="timeDisplay" class="ui-slider-handle" tabindex="0" style="width: inherit !important; height: 3em; padding-left: 1em; padding-right: 1em; white-space: pre-wrap; text-align: center;top:-1em;"></div>
+					</div>
+				</div>
 			</div>
 		</div>
 

override.js

@@ -226,7 +226,11 @@ function activateOverride() {
 
 	// Calculate end time for override
 	let endTime = Math.floor(Date.now() / 1000) + (gClockOffset * 60) + (gOverrideMins * 60);
+	changeOverride(endTime);
+}
 
+// Activate override or change endtime [with second-precision]
+function changeOverride(endTime) {
 	// Request override
 	let message = {
 		type: "override",
@@ -244,6 +248,40 @@ function activateOverride() {
 			$("#alertOverrideSetList").html("<ul><li>" + gOverrideSetNames.join("</li><li>") + "</li></ul>");
 		}
 		$("#alertOverrideActivated").dialog("open");
+
+		//Update override time
+		let minDate = Date.now();
+		let fixTime = function(sliderDate) {
+			$("#timeDisplay").text( timeDiffToStr(sliderDate-minDate) + "\n" + sliderDate.toLocaleTimeString() );
+		};
+
+		//keep the remaining time counting from a UI-perspective
+		setInterval(function(){
+			minDate = Date.now();
+			fixTime(new Date($("#slider").slider("value")));
+		}, 60*1000);
+		$("#slider").slider({
+			min: minDate,
+			max: endTime,
+			value: endTime,
+			range: "min",
+			create: function() {
+				let sliderDate = new Date($(this).slider("value"));
+				fixTime(sliderDate);
+			},
+			slide: function( event, ui ) {
+				let sliderDate = new Date(ui.value);
+				fixTime(sliderDate);
+
+				//Add a Update-Button
+				$("#alertOverrideActivated").dialog("option", "buttons", Object.assign({
+					Update:function() {
+						//$(this).dialog("close");
+						changeOverride($("#slider").slider("value")/1000);
+					}
+				},$("#alertOverrideActivated").dialog("option", "buttons")));
+			}
+		});
 	} else {
 		// Close page immediately (no confirmation dialog)
 		closePage();
@@ -311,6 +349,10 @@ $("#alertOverrideActivated").dialog({
 	close: function (event, ui) { closePage(); }
 });
 
+function timeDiffToStr(diff) {
+	return Math.floor(diff/3600000)+":"+(Math.floor(diff/60000)%60).toLocaleString('en-US', {minimumIntegerDigits: 2});
+}
+
 // Initialize access control prompts
 initAccessControlPrompt("promptPassword");
 initAccessControlPrompt("promptAccessCode");