open in same window, when using simple finder window

I assume you're in Icon view.

In which case the answer appears to be no.

Try Column view - you just track them across the window then and it makes no odds if you have the sidebar showing or not.

Two ways you can do that -

For a one-time purpose, hold down the Option key while double-clicking the icon of the folder in the window - it will be opened in the same window.

For a global 'always' setting, go to Finder Preferences (Preferences in the Finder menu), General tab, and uncheck the item "Always open folders in a new window".

Thanks for the correction ref. the opt key, Don. However I always have the finder selection unchecked and in icon view it still opens new windows…

noondaywitch wrote:

Thanks for the correction ref. the opt key, Don. However I always have the finder selection unchecked and in icon view it still opens new windows…

Odd. When I check or uncheck that item in Finder Preferences, the resultant behavior is as expected in all folder view modes, including Icon view.

Finder menu: View > Show Toolbar (option-command-T)