"selection" in export dialog should be greyed out if no object is selected

Consider this sequence:

1) no object is selected
2) the Selection button is pushed -- no difference to the export area
3) a selection is made -- the export area changes immediately

It seems to me that pushing the Selection button has an effect even if there currently is no selection, and therefore it shouldn't be grayed out.

Do you see any further advantage in graying it out?

Hm, for me, if no object is selected and the Page button is pressed down, if I push the Selection button, it jumps to the Drawing button instead. Hence, the Selection button "doesn't work".
If I select a object, I expect the Selection button to go from inactive to active, just like the Add button in gtkfilechooser gets active if a folder is selected.

When no object is selected, the Drawing button becomes a temporary default fall-back for the Selection button. The export will always work with the Selection button, regardless of whether an object is selected or not. "When nothing is selected, everything is selected."

To me, it seems that making the button inactive when no selection exists would only make procedures more complicated. For instance, if I have a drawing with several objects and I want to have individual bitmaps of them, I can push the Selection button, select the first object, Export, select the next one, Export, etc. With your suggestion, it would be: select the first object, push the Selection button, Export, select the next object, push the Selection button, Export, etc, as the button would be inactivated at the point when one object is unselected prior to the next becoming selected.

You don't need to push the Selection button after you have selected a object on the canvas. It gets selected automatically.

My mistake. I've never done it in that order before, so I didn't know that the exporter dialog changes from Page/Drawing to Selection when a selection is made.

The way I see it, the buttons are a slightly awkward variant of the typical printing dialog -- maybe it should use radiobuttons and look like this instead:

Export
  (*) Page
  ( ) Drawing
  ( ) Selection
  ( ) Custom

Anyway, I'll confirm it, and maybe a developer will pick it up.

Same thing for the Drawing button when the drawing is empty (even if it's a bit weird to export an empty canvas).