Every time PL/SQL Developer is opened, the windows on the left side of the main interface are "Link", "Object" and "Window List" in sequence, but the "Object" window is often used, so under normal circumstances I will use "Link" and "Window List". The "Window List" two windows are closed or hidden. But I found a disadvantage, that is, after each restart of PL/SQL, the left window of the main interface will turn into the following figure 1, that is, the user's window settings are not saved.
Solution: first set the custom "main interface left window" settings, then as shown in Figure 2, in the menu Tools -> Preferences -> User Interface -> Options window, tick "Auto save desktop" That's it. Re-open PL/SQL, and the settings in the left window of the main interface will be displayed according to your last settings.