Saving "locked" state of toolview

[Vladimir Prus]

Right now, when one starts KDevelop4, all the toolviews are "unlocked"
by default -- the disappear automatically. I find this somewhat annoying
for the debugger views at least, and I see several possible solutions:

1. Just kill the notion of "unlocked" tool. Make them disappear only
by explicit user click.

2. Store the "locked" state:

2.1 Store it per-application, so that if left tool area is locked, it's
locked in all areas.

2.2 Store it per-area

Any opinions?

Suppose, for simplicity, that we took took approach (1) and all toolview
appear when one clicks on toolview's button and disappear either when
we click on the same toolview's button again, or click on other toolview's
button.

In that case, we still have the question if any tool should be visible
when one opens KDevelop, and if so, which one. For this case, it seems
clear to me that we should store this information per-area. Say,
when we start in Code area, we probably want the project manager to be
visible. When we start Debug area, we probably want something else
to be visible.

Is there agreement about this bit?

- Volodya