I relaxed a bit by implementing something that was missing in Grapher.

Consider the following code:

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b := RTGrapher new.

ds := RTDataSet new.
ds points: #(5 10 6 2 -2.5).
b add: ds.

“below is the magic line"

b addDecorator: RTCursorFollower new.
b

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This “magic line” add two bar that follows the mouse cursor. Here is a screenshot:

Here is on a larger example:

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| methods trachelMethods b ds |
methods := Collection withAllSubclasses flatCollect: #rtmethods.
trachelMethods := TRObject withAllSubclasses flatCollect: #rtmethods.

b := RTGrapher new.
b extent: 200 @ 200.

"Data set 1"
ds := RTDataSet new.
ds interaction popup.
ds dotShape circle color: (Color red alpha: 0.3).
ds points: methods.
ds x: #numberOfLinesOfCode.
ds y: [ :m | m getSource size ].
b add: ds.

"Data set 2"
ds := RTDataSet new.
ds interaction popup.
ds dotShape circle color: (Color blue alpha: 0.3).
ds points: trachelMethods.
ds x: #numberOfLinesOfCode.
ds y: [ :m | m getSource size ].
b add: ds.

b axisX withThousandsSeparator; title: 'LOC'.
b axisY noDecimal; title: 'Size'.

b addDecorator: RTCursorFollower new.
b build.

^ b view

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Maybe this cursor follower should be per default in all produced chart. Any opinion?

Cheers,

Alexandre