hi Pierre,
sorry, this (0.9.86) isn't doing what I expect... Pressing F11 makes the layout alternate between the the panes being visible, and then getting undocked and relocated way down in the corner such that only part is visible... Or else, in a layout where I have HTML and Properties as tabs within the same pane, pressing F11 randomly puts now the HTML Pane, now the Property Pane down into the corner, leaving the other pane in place.
[edit: just noticed David_H has reported the same issue in the announcements forum, and a bit more clearly as well!]
DavidF.