Initial mousedown in range selection causes rangeSelectionChanged with finished set true

[MarquisDeMizzle]

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[x] bug report => search github for a similar issue or PR before submitting
[ ] feature request
[ ] support request => Please do not submit support request here, instead see https://github.com/ceolter/ag-grid-enterprise/blob/master/CONTRIBUTING.md#question

Current behavior

The mousedown when initiating a range selection fires a RangeSelectionChangedEvent with finished == true. Dragging then generates the expected sequence of RSCE's bookended by started and finished.

Expected behavior

This mousedown should either not generate a RSCE or generate the started == true event.

Minimal reproduction of the problem with instructions

Add onRangeSelectionChanged handler that logs the event's finished value on any grid with range selection enabled, such as the plunker from https://www.ag-grid.com/javascript-grid-range-selection/#range-selection-example-suppress-multi.

What is the motivation / use case for changing the behavior?

Situation where user must select a range at least 2 rows tall or selection automatically clears. Initial mousedown finished == true event causes this "exceptional" case to immediately trigger.

Please tell us about your environment:

Debian 9.5: 4.9.0-7-amd64 #1 SMP Debian 4.9.110-1 (2018-07-05) x86_64 GNU/Linux

• ag-Grid-Enterprise version: 2.0.X

Observed in 18.0.1 on my system Observed in 18.1.1 via documentation Plunker

• Browser: [all | Chrome XX | Firefox XX | IE XX | Safari XX | Mobile Chrome XX | Android X.X Web Browser | iOS XX Safari | iOS XX UIWebView | iOS XX WKWebView ]

Chrome Version 67.0.3396.99 (Official Build) (64-bit) Firefox ESR 52.9.0 (64-bit)

• Language: [all | TypeScript X.X | ES6/7 | ES5] ES6