This page is here to list possibles single click policy, and evantual problems they may introduce
They are several reasons to switch to a single click policy.
One is that it would improve gnome accessibility. Double click is impossible to perform for certains persons. There's a double click emulation that can be configured in gnome, but having a default single click policy as default would be far better.
Double click is used to enable several actions to be binded on the same button. Thus one can select elements and perform a default action with the same buttons. Binding multi actions on a single button is clearly not a good policy.
Today most pointer devices have several buttons, often three, which is more than you need for manage selection and default action on separated buttons.
Moreover gnome aims to be usable on plateforms like e-tablets, where touchscreen is often the main input device. Using a double click there would also be a very bad policy.
Last but not least : users want it. Bug reports show people really want this feature.
We made a big change with gnome-shell, so "users fear changes" can't be used as a valid arguments here. Gnome aims to be a convenient, accessible desktop, not a desktop which keep bad behaviours because they are behaviours.
An other complaint could be "how do I select/default-action my elements with my single button pointing device mom bought me when I was a child ?".
A possible answer is to use an alt key on the keyboard if you are using a desktop computer. And if you are not, you probably can't plug mom's device, can you ? This is just an example and other propositions may appear bellow.
State of the art
You can set a single click policy through nautilus, but it won't be followed everywhere and mainly in the gtk file chooser widget. This is in some way even worst than no single click policy at all as it confuse user with multiple policy depending on which file navigator she's using.
A bug is open since a long time on this subject : https://bugzilla.gnome.org/show_bug.cgi?id=121113
No idea. Contribute !
Single click was well integrated at least a decade from now, even this is not the default policy.
Drop the multi click management completely, with no option to make it happen again. This may be a little rude. Without speaking of some applications specifics behaviours, this would remove "double click select a word, triple click select a line".
Primary button binded to default action Second button binded to selection Third button binded to contextual menu
Note that, on desktop, most keyboard offers at least 5 switch behaviour, ie : alt, alt gr., shift, ctrl, super. For single buttons pointers ctrl is already used as a "select one element" switcher, and shift as a "select until here". For contextual menu, most keybord already have a special key. Moreover clicking on the background with the primary button enable to draw a selection rectangle.