PerspectiveWidget gets in unrecoverable state

[robambalu]

Reproduce the issue:

• create a multi-line d3_y_line graph
• go to the edit settings, change view to datagrid
• go back to y-line

at this point the graph will only show 1 of the lines, and going into edit wont let you choose multi lines again either ( seems to be in an unrecoverable state at this point )

sample graph:
import pandas
x = pandas.DataFrame( { "a" : list(range(10)), "b" : list(x*x for x in range(10))})
perspective.PerspectiveWidget( x, plugin='d3_y_line')

after going through3 steps above:

[texodus]

Use shift+click on the inactive columns to additional columns when in chart mode, or drag/drop them from bottom to top (this is just the reverse of the behavior of click and shift+click in Datagrid mode).

There is a bug here in PerspectiveWidget though - setting plugin to "d3_y_line" without also explicitly setting columns should not default to all columns (as it does currently), but rather should display the behavior shown in your screenshot, e.g. choose a single numeric column if one is not already in the 1st position of the column selector. To get the chart you want, the (intended) API would be:

import pandas
x = pandas.DataFrame( { "a" : list(range(10)), "b" : list(x*x for x in range(10))})
perspective.PerspectiveWidget( x, plugin='d3_y_line', columns=["a", "b", "index"])

[robambalu]

I see, ctrl+shift does seem to let me add them back in, but its odd to see it drop them all by switching to datagrid and then back ( also, I may be missing it, but why the need for ctrl+?)