Which JMP version are you using? What would you like to display? Those different bars do have possibility of showing different hover labels but it might require some extra work, Scripting Guide > Scripting Graphs > Hover Labels > Work with the Hover Label Execution Context .
You can play around with this example to try and understand what you could do (local:_measurements is what you need)

JSL Variables
local:encodedWhere = XML Encode(local:_where);
Show(Namespace("local") << Get Contents());
HTML Markup
<b>Groupings</b>: {local:_groupings}
<b>Measurements</b>: {local:_measurements}
<b>Summary statistic</b>: {local:_summaryStatistic}
<b>Filter columns</b>: {local:_filters}
<b>Where clause</b>: {local:encodedWhere}
<b>Graph type</b>: {local:_displaySegName}
<b>Data table</b> {local:_dataTable}
<b>Drill depth</b>: {local:_drillDepth}
<b>First Row</b>: {local:_firstRow}
<b>Underlying Rows</b>: {local:_underlyingRows}
Notice that Measurements is different

-Jarmo