RFR: JDK-8290016: IGV: Fix graph panning when mouse dragged outside of window

[Tobias Hartmann]

On Tue, 12 Jul 2022 13:48:16 GMT, Tobias Holenstein <tholenstein at openjdk.org> wrote:

> A graph in IGV can be moved by dragging it with the left mouse button (called panning). 
> ![panning](https://user-images.githubusercontent.com/71546117/178509416-24dd900f-131b-484b-af47-c7a78e791434.png)
> 
> If the mouse left the visible window of the graph during dragging, the diagram started to move in the opposite direction. This was annoying. Now panning stops as soon as the mouse leaves the window. 
> ![stop reverse panning](https://user-images.githubusercontent.com/71546117/178509309-3df03b7a-ada4-45a3-b9a7-d6e10664033d.png)
> 
> In selection mode, the graph still moves when the mouse is dragged outside the window, as this is meant to make a larger selection. 
> ![keep panning for selection](https://user-images.githubusercontent.com/71546117/178509302-74fa41d2-e611-40a3-b6b0-c937ef4b2462.png)

Changes requested by thartmann (Reviewer).

src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/actions/CustomizablePanAction.java line 149:

> 147:             scrollPane = null;
> 148:         }
> 149:         return state ? State.REJECTED : State.REJECTED;

That does not look correct.

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PR: https://git.openjdk.org/jdk/pull/9470