toolbar.js: Ensure toolbar handle cannot be dragged outside window

[teddywing]

Previously the toolbar handle could be dragged beyond the top and bottom
of the window where it could get lost.

If the handle position outside the window border was saved, the only way
to get the handle back that I found would be to open the inspector and
manually change the handle's offset to make it visible once again.

This change restricts the handle so that it cannot be dragged above the
top or below the bottom of the window area.

Closes #634.

[tim-schilling]

I tested this out and it works for the functionality you described, but breaks when I scroll down a page or two and then try to move the toolbar.

[teddywing]

Sorry about that. Thanks for taking a look. Admittedly I only tested this on the sparse index page. I'll work out the scrolling issue you described.

[teddywing]

Made the following update to handle scrolling:

diff --git a/debug_toolbar/static/debug_toolbar/js/toolbar.js b/debug_toolbar/static/debug_toolbar/js/toolbar.js
index c42e885..7bd1045 100644
--- a/debug_toolbar/static/debug_toolbar/js/toolbar.js
+++ b/debug_toolbar/static/debug_toolbar/js/toolbar.js
@@ -140,7 +140,7 @@
                     // cursor really moved.  Otherwise, it will be impossible to expand the toolbar
                     // due to djdt.handleDragged being set to true.
                     if (djdt.handleDragged || event.pageY != startPageY) {
-                        var top = baseY + event.pageY;
+                        var top = baseY + event.clientY;

                         if (top < 0) {
                             top = 0;
@@ -148,7 +148,7 @@
                             top = windowHeight - handle.height();
                         }

-                        handle.offset({top: top});
+                        handle.css({top: top});
                         djdt.handleDragged = true;
                     }
                 });

[tim-schilling]

Thanks! I'll try to take a look at it and get it merged in this week.

[teddywing]

Thanks

[tim-schilling]

Thanks for the PR!

[teddywing]

Thank you!