fixes

1-js/05-data-types/11-date/article.md

@@ -33,6 +33,13 @@ To create a new `Date` object call `new Date()` with one of the following argume
 
     It's a lightweight numeric representation of a date. We can always create a date from a timestamp using `new Date(timestamp)` and convert the existing `Date` object to a timestamp using the `date.getTime()` method (see below).
 
+    Dates before 01.01.1970 have negative timestamps, e.g.:
+    ```js run
+    // 31 Dec 1969
+    let Dec31_1969 = new Date(-24 * 3600 * 1000);
+    alert( Dec31_1969 );
+    ```
+
 `new Date(datestring)`
 : If there is a single argument, and it's a string, then it is parsed automatically. The algorithm is the same as `Date.parse` uses, we'll cover it later.
 

2-ui/3-event-details/1-mouse-events-basics/article.md

@@ -21,6 +21,9 @@ The most used simple events are:
 `mousemove`
 : Every mouse move over an element triggers that event.
 
+`contextmenu`
+: Triggers when opening a context menu is attempted. In the most common case, that happens when the right mouse button is pressed. Although, there are other ways to open a context menu, e.g. using a special keyboard key, so it's not exactly the mouse event.
+
 ...There are several other event types too, we'll cover them later.
 
 ### Complex events
@@ -28,9 +31,6 @@ The most used simple events are:
 `click`
 : Triggers after `mousedown` and then `mouseup` over the same element if the left mouse button was used.
 
-`contextmenu`
-: Triggers after `mousedown` if the right mouse button was used.
-
 `dblclick`
 : Triggers after a double click over an element.