RFR: 8345039: IGV: save user-defined node colors to XML

[Emanuel Peter]

On Thu, 28 Nov 2024 15:15:06 GMT, Tobias Holenstein <tholenstein at openjdk.org> wrote:

> This PR depends on https://github.com/openjdk/jdk/pull/22402 
> 
> [JDK-8343535](https://bugs.openjdk.org/browse/JDK-8343535) introduced the possibility to give user-defined colors to a node.
> The colors are lost when the user goes to the next graph or when IGV is closed. Save the colors as a property of the graph to the XML to make it more permanent. This requires that the user can also remove the colors again.
> 
> <img width="474" alt="color" src="https://github.com/user-attachments/assets/c994f93c-7db1-40e6-9963-2f5417cec77f">
> 
> ### Whats new
> - Now colors are saved with the XML as well
> - Colors are kept when changing to a different graph
> - The user can remove the color again: This uses the color from the filter or WHITE otherwise

Looks good, thanks Toby!

A quick review from a non-IGV engineer ;)

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Marked as reviewed by epeter (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22440#pullrequestreview-2468462635