[AnotherCat]

A simple example might be of use.

For security reasons my display is set to turn off after 3 minutes of user inactivity. Other users may have different reasons if security is not a consideration e.g. to save battery on a notebook or on a Windows tablet. Commonly one will hit ENTER to restore the display (any key will do so but I think for valid reasons many often use ENTER).

A demonstration example is that if one has Calibre as the active window with a record (book) highlighted, and if one uses the Open With plugin and has any selection in its dropdown highlighted then if the display times off and one restores it by hitting ENTER twice (easy to do if it is slow waking), or even hit any key then ENTER (as one might do if the display is slow opening) then the selected application in Open With will run.

Now that is correct behavior for a database. Currently, if one has a record selected and hit ENTER, nothing happens; if one has a record selected and an application in Open With selected and hit Enter then that application opens. That is acceptable behavior in the context of the non critical context of Calibre even though in the case of waking the display from sleep it may not have been that one wanted the selected application to run (but as one had it selected before the display turned off it is likely that the next action one wanted was for it to open). One has selected a record AND one has selected an application to run.

If the default behavior of Calibre is changed so that hitting ENTER with a record selected only, and that opens a viewer (I'm assuming it will still open ones default viewer), every time one restores ones display, after it turns off, with one or more key presses one of which is an ENTER then one will find oneself with the viewer application running and oneself in that (assuming that case cannot be coded out of the default behavior in the tweak). That is not correct behavior for a database.

That is just one example of possible misbehavior for a database.