"Close all configuration windows" button: perhaps change it to a toggle

[evertrol]

The "close all configuration windows" button could be a toggle instead. Currently, it closes all open configuration windows. Clicking it again does nothing; for a few seconds, I had hoped it would open all configuration windows instead.

If the button acts as a "toggle all configuration windows" (or with a tooltip telling the user whether it will close or open all configuration windows, depending on the current state), it is perhaps more straightforward what it will do. The preferred direction of the initial toggle (open all or close all) may be on the relative amount of currently opened configuration windows.

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As a minor enhancement (not opening a separate issue for this): perhaps the icon could be changed to a multiple cogwheel icon, reflecting the single gear on individual graphs. Currently, the icon is the almost-standard "photo - picture" icon. (Users will be trained quickly enough about this particular icon use though, especially thanks to the tooltip.)