Hello michka,
Firstly I have moved your post.
Please try to post in a section of the forum relevant to your question.
All that has happened is you have turned of the 'Quick Select' magnet in the arrow (selection) tool.
The Spacebar is the keyboard shortcut for this option.
Personally I like to leave it off and use the spacebar to toggle it on when needed.
Otherwise I find I am always selecting roofs, fills, slabs, etc., when ever I click to let go of selected objects as the quick select will select the surface of these elements if it is active.
When it is off i can click in any space to deselect.
Barry.
One of the forum moderators.
Versions 6.5 to 27
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