In application Scidb I have three tabs in main notebook: Information, Database, and Board. Sometimes it happens that when switching from Database tab to Information tab (via mouse click in tab bar) the Information tab is flickering a short time, and then the Database tab is still visible, although the Information tab is displayed as selected in tab bar.

I found out that sometimes via a geometry request the function NotebookPlaceSlaves() (ttkNotebook.c) will be triggered after function SelectTab() has been entered, but before the current index is set to new tab index, and this function will change back to previous tab (current index = Database tab), because this function is not regarding the index of the active tab, in this case it's the newly selected Information tab.