202 Cell navigation tutorial

[koyllis]

When you navigate the grid with left or right arrow the header stays the same!
It should move with cell.. horizontal scrollbar works ok!

[PaulL1]

I have this issue as well. It looks to me to be driven by the cellNav routine triggering the scroll through a setFocus on the new cell. This automatically triggers a scroll event in the viewport, which seems to process it fine. However, the viewport appears to assume that a viewport scroll would always have been triggered from a GRID_SCROLL event which I think is against the render container. There doesn't look to be a process to trap the scroll at the viewport level and push it up to the render container and/or to tell the native scrolling that it should propagate to the render container.

My suggested solution is to drive off the grid debounce - which tells us when the grid has triggered a scroll event, as either isScrollingHorizontally or isScrollingVertically is true. If we get a scroll event on the viewport without one of those set, then it is a native scroll and not from the grid controller, it is probably triggered from cellNav. In this situation, fireScrollingEvent to let the grid know the scroll the header too.

The main drawback of this solution is that the grid debounce wasn't intended for this purpose, and it goes away on a 300ms timer. If we get scroll events within 300ms (say, someone holding down the right arrow) then we'll still get the header out of sync. This could be fixed by putting in additional "isScrolling" variables, but that seems untidy, so I'll hold this open for discussion first.

[PaulL1]

@swalters: would be good if you could review this with your cellNav updates in mind. Potentially your approach there might mean this isn't a problem - so I'm going to leave this to see that solution. If already fixed then very good, if not then I can do the work to add a new property to the grid, then look at it instead of the debounce property. It's kind of ugly, but I haven't thought of anything better yet - hoping that you might.

[PaulL1]

Believed to be fixed via recent cellNav updates.