Hi rado - if you first click-select just one edge, then the window select (where you click and drag out a selection rectangle) will only target other edges inside that same solid instead of any faces in it.
But it sounds like you want to select independent curve objects that were used to create the solid, rather than the edges of the solid (which are sub-objects that belong to the solid rather than independent).
There isn't currently any automatic way to limit the window selection to only target independent curve objects only, but if you start the window to the left side and drag it towards the right, only objects that are fully contained within the window will be selected. Sometimes you can use that at strategic locations to grab a bunch of smaller curve objects that are in the same area.
Otherwise, as you have probably seen if you move your mouse over top of a solid before it is selected, any curve objects that are floating around on top of it will be targeted, so that generally works for getting the independent curves with a click, one at a time.
Other than these methods, it is possible to set up a keyboard shortcut that will select all independent curve objects. To do that, set up a keyboard shortcut and set this as the command:
script:moi.geometryDatabase.getObjects().getCurves().setProperty( 'selected', true );
Then when you push that curve it will add only "standalone" curve objects to the selection and you can delete or hide them.
Also Petr has made a custom command to help with selecting objects by type, which may be useful:
http://kyticka.webzdarma.cz/3d/moi/#SelectByType
I do plan on adding a kind of "selection filter" mechanism which would let you restrict the window selection to certain kinds of objects like you want here, but it may be a little while yet before I am able to make that part work.
- Michael