[Qgis-developer] Changing ergonomy of the visibility of layers inside groups ?

[Even Rouault]

> Another scenario would be:
> 
> When clicking, the group toggle between unchecked, partially checked,
> checked. At the same time it caches the state for all subitems to
> restore the partially checked state when switching to this.
> 
> At any time, when a subitems check state is changed, all parents
> invalidate their cached states and override it with the new partial
> check state. If the last remaining unchecked item is checked (and vice
> versa) clicking the group skips the partially checked state...
> 
> Maybe that would be more natural?

So imagine you have an initial state with a group G checked and its layers A 
and B checked
You click on G ==> it becomes unchecked, and A and B as well
You click on G ==> it becomes checked, and A and B as well
You click on A to unselect it ==> G becomes partially checked. And you save 
current state of A and B as StatePartial
You click on G ==> it becomes checked, and A and B as well
You click on G ==> it becomes unchecked, and A and B as well
You click on G ==> it becomes partially checked, and you restore StatePartial 
(ie A is unchecked and B is checked)
You check on A ==> it becomes checked and G as well (and clicking on G would 
switch between all on - all off)
You uncheck A --> G becomes partially checked
You uncheck B --> G becomes unchecked  (and clicking on G would switch between 
all on - all off)

Is that what you meant ? That makes sense to me.
Besides a slightly more complicated implementation, one downside would be that 
cycling between (partially)on state and off state of a group (with different 
check state of its items) would require 1.5 clicks on average (1 click to go 
from unchecked to partially checked, 2 from partially checked to unchecked) 
instead of 1. I should check with the users if they can afford the extra half 
click :-)

Thanks for your suggestions.

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