NavTertiaryList scroll bugs

[rhamilto]

In OpenShift console, we have tabbed navigation that can include more tabs than can be displayed at a given viewport. NavTertiaryList seems like a good way for us to solve for this problem. However, I've noticed a few bugs in attempting to implement NavTertiaryList in OpenShift console (see openshift/console#3096).

• In my OpenShift console prototype, the scroll buttons don't appear on initial load. Resizing the viewport fixes the bug. Initialization bug?
• Sometimes clicking the scroll buttons doesn't result in scrolling in the entire nav bar (stops short and remaining tabs are never revealed no matter how much clicking occurs).
• Rapidly clicking the scroll button can result in the first or last tab being selected, which can be confusing (see below). In my OpenShift console prototype, I accounted for this by not overlaying the scroll buttons on top of the tabs.
  
• Scrolling the nav with the mouse pointer instead of the buttons does not show or hide the buttons when reaching the beginning or end of the scrollable area.
  
• Font weight increase for active item causes a "shimmy" of the nav items on select, and the last nav item can end up clipped.
  

cc: @spadgett

[rhamilto]

cc: @janwright73

[nicolethoen]

• Rapidly clicking the scroll button can result in the first or last tab being selected, which can be confusing (see below). In my OpenShift console prototype, I accounted for this by not overlaying the scroll buttons on top of the tabs.
  

• Font weight increase for active item causes a "shimmy" of the nav items on select, and the last nav item can end up clipped.
  

@mcarrano @mcoker I believe both of these points are going to need to be design/core changes. I will open two issues in Core for these points.

[nicolethoen]

Still waiting on patternfly/patternfly#2435