Editing Tileset Image properties is unintuitive

[eishiya]

A question that repeatedly comes up is how to modify any of the properties associated with a Tileset Image, such as the tile size and transparency colour. You have to click the value of the Image property, and then click the Edit button that appears. That value is a filename, so it looks like it would just be for editing the source, and trying to click on any of the specific properties you want to edit does nothing and they are greyed out, so it's easy to believe that you can't change them at all and have to start your Tileset over.

Ideally, I think these properties should be editable like any other, instead of being in a separate dialog. It would be very convenient and educational to step through different size, margin, and spacing values and see how they affect your tiles, for example. If #2866 is implemented, then temporary live edits won't mess up the user's maps or pop up any annoying prompts.

Failing that, perhaps double-clicking any of the values (Image itself and any of its subproperties) should bring up the Edit Tileset dialog, with the relevant field focused, if possible. Or the Edit button could show up in the Image field if you click any of the subproperty values. At the very least, clicking* the name of the Image property should show the Edit button - having to specifically click the value makes this hidden feature even harder to find. * Merely navigating to the Image property via keyboard shouldn't activate the Edit button though, that behaviour should stay as-is.