Added a new tool icon.

In D1588#63834, @vladislavbelov wrote:

It'd be good to get first item from the list.

Could I ask for feedback again?

Added default object for the Placement tool.

I think default is good, because as I mentioned above, we have the default logic for the Paint Terrain tool.

Try it out please. A new icon for the tool would have to be made, for now I gave it the same one as the Move tool. ATM if you start the editor and select the Place tool without selecting any object first, a warning is written out in the window - should I leave it like this, or try to grey the button out? Or maybe automatically select the first item in the list? Not sure.

Added "Place" tool to the toolbar.

Yeah, if I changed the current double click solution to a single click, that would be an acceptable minimal solution to the ticket. But adding the new Placement tool/mode is better IMHO as it solves a deeper underlying problem. Adding unnecessary UI is definitely bad, but here it makes sense, is consistent with the rest of the GUI and makes it more predictable, because the rule seems to be:

In D1588#63740, @vladislavbelov wrote:

The problem, that we don't have a visible tool for the object placement. So I can suggest to add this tool. It can be together with the doubleclick.

In D1588#63744, @elexis wrote:

I'm not good with wxWidgets either, doesn't EVT_COMMAND_LEFT_CLICK do what we want? http://docs.wxwidgets.org/3.1/classwx_command_event.html (I don't recall if we still support wx 3.0, not unlikely do)
(Notice that we'd still need the EVT_LISTBOX event for keyboard induced selectionchanges as far as I see)

Isn't atlas supposed to activate the placer tool again once the objects tab is activated again (i.e. independent of the means to activate the panel)?