Restore the subtlety of window position

Many applications implement such a feature ： They record the last position on the screen when the window is closed , And try to restore these locations when the application restarts . If you simply implement this function , Then most developers will unconditionally record the last display position of the window , And when the program restarts, restore the window to this position .

however , This may cause usability problems for your program , How to say this? ？

If the user runs two instances of your program , Then the two windows will eventually appear in exactly the same position on the screen . Unless the user looks at the taskbar carefully , Otherwise, when running the second instance , It doesn't seem to have any effect .

Now things are starting to get interesting . Depends on what the program does , The second instance may encounter sharing conflicts , Or it may just open the second copy of the document for editing , Or you may start playing two copies of the song , Which leads to strange echo effect , Because these two instances are not synchronized in time .

More interesting , If the user clicks the stop button , Instead, the music continues to play ！ Why? ？ Because only the playback of the second instance is stopped , The first instance is still running . I know that a user often runs up to four instances of multimedia titles , This will cause terrible noise , Because they all play attractive music at the same time , Then it causes a lot of confusion when users try to solve the problem , This usually includes tapping on the top instance “ stop it ” Button .

however , This will only stop the top-level instance , But the other three are still running …… If you open the second copy of the document , Users may switch from editor , Then switch back to the first instance , And think all the changes are lost . Or the user may not notice this and make a set of conflicting changes to the first instance . then , When saving two copies of the same document , All kinds of interesting things will happen .

The moral of the story ： If your program saves and restores its screen position , You may need to check whether another instance of the program is already running at this screen location . If so , Then move the second window to another location , So that it does not occupy exactly the same coordinates .

summary

Don't worry ,TopomelBox Only one instance can be opened in the whole process , If the user clicks the program icon for the second time , The previous instance will be automatically activated .
Why not support multiple instances , In fact, my younger brother is incompetent , Wait until the wings are hard .

Last

Raymond Chen Of 《The Old New Thing》 It's one of my favorite blogs , There's a lot about Windows Little knowledge , For the vast Windows For platform developers , It's really helpful .
This article is from ：《A subtlety in restoring previous window position》