Testing locally noticed these issues:

1. the report doesn't seem to be centered, might look better if it was

2. If I click in the transitions report, I see a popup like this

and then the report is empty

3. the select dropdown is under the report

@mattab UI needs approval

the report doesn't seem to be centered, might look better if it was

I didn't manage to center it but I actually think it's fine like this anyway. Feel free to give it a try. It's so hard to do much there I think cause the transitions JS is quite complex and built for popup etc.

If I click in the transitions report, I see a popup like this

had actually no idea it was clickable... i think the JS is not able to render 2 transition reports on the same page or it's trying to alter something.
It should more or less work now. If there's still a problem I will need to disable the onclick functionality in this report.

the select dropdown is under the report

should be fixed

also applied the other feedback @diosmosis

LGTM just need UX approval from @mattab & UI tests

fyi: merged 3.x-dev into this PR. Fixed system test & ui tests. Added UI tests (need to update again once the build has finished). The UI test show something funny for transitions page titles but checked and this seems to be actually a general issue of transition, not related to the integration etc. UI should be fine for now, don't think we need to wait for it to merge re @mattab

Tests should be fixed now.

Was going to merge, but the transitions widget looks a bit off:

Guess the page title shouldn't display in the dashboard.

I think something in the code is also causing the UI test on travis to have issues (works fine for me locally): https://builds-artifacts.matomo.org/matomo-org/matomo/12865/31592/UIIntegrationTest_dashboard3.png

Think it might have something to do w/ the width of an element.

@diosmosis I think I fixed the remaining issues this morning

Looks really good overall, it's nice to know more users will discover this feature.
Feedback:

• In the footer message eg. Simply hover a row in any of these reports and click on the transition icon to launch it. could maybe add the Transitions icon in the text itself.
• Add a "Help text" for the report, that 1) gives a quick explanation of what the report is, and 2) links to: https://matomo.org/docs/transitions/
• When viewing the transitions for a site, and changing site, then I get error:

Please specify a value for 'actionName'.#0 /core/API/Proxy.php(157): Piwik\API\Proxy->getRequestParametersArray(Array, Array)#1 /core/Context.php(28): Piwik\API\Proxy->Piwik\API\{closure}()#2 /core/API/Proxy.php(323): Piwik\Context::executeWithQueryParameters(Array, Object(Closure))#3 /core/API/Request.php(263): Piwik\API\Proxy->call('\\Piwik\\Plugins\\...', 'getTransitionsF...', Array)#4 /plugins/API/Controller.php(41): Piwik\API\Request->process()#5 [internal function]: Piwik\Plugins\API\Controller->index()#6 /core/FrontController.php(564): call_user_func_array(Array, Array)#7 /core/FrontController.php(152): Piwik\FrontController->doDispatch('API', false, Array)#8 /core/dispatch.php(34): Piwik\FrontController->dispatch()#9 /index.php(27): require_once('/home/matt/dev/...')#10 {main}

• in case it's possible, would be nice if we could re-draw the Transitions report when the browser window is resized (currently the Transitions report is not re-drawn and will overflow or look small)

• added the icon
• added help text & link
• couldn't reproduce an error when switching site.... added some code maybe it helps
• No we cannot resize it, it's a "miracle" it was possible to embed it at all