RFR: 5721: Reintroduce the Percentage column

[Marcus Hirt]

On Mon, 16 Dec 2019 16:47:47 GMT, Henrik Dafgård <hdafgard at openjdk.org> wrote:

>> This patch addresses [JMC-5721](https://bugs.openjdk.java.net/browse/JMC-5721): Reintroduce the Percentage column.
>> 
>> 1. StacktraceView has been amended to display Percentage column as well it displays stack trace and count ones. Percentage format is #.## (up-to 2 decimal points), it will also arbitrarily round the number.
>> 2. Tool tip with frame fraction and sibling groups info has been moved from Count column to Percentage.
>> 3. Currently Background drawer decorates Percentage column instead of Count.
> 
> 

Hi Dmitry! 

We're using ISO 8000-1 in the JMC project. This means we actually prefer having a space in there, not only between values and units, but also between values and symbols like the percent sign. 

See e.g.:
https://physics.nist.gov/cuu/Units/checklist.html, https://www.euspen.eu/wp-content/uploads/2018/08/A-Style-Guide-For-euspen-Publications-2017.pdf

That said, I agree that sticking to two decimals for the rendering looks neater. I believe the default rendering for PERCENT_UNITY is to try to use up to 3 significant figures, switching to scientific notation if the value is too large/small, which perhaps would be a good representation for the tooltips?

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PR: https://git.openjdk.java.net/jmc/pull/12