1/ Minimise apps into their icons — You can click the yellow pill button in the upper left corner of a window to minimize an app’s window into the Dock in macOS Sierra, but if you minimize a lot of windows, the right side of the Dock quickly becomes cluttered.
The solution is to minimise windows into their app icons.
Open System Preferences from the Apple menu and choose Dock. Check the box next to ‘Minimize windows into application icon’ (shown above). Now they minimise down into the originating app’s icon – click-and-hold on that in the Dock to see your files (below).
If you have a lot of minimized app windows, and have trouble finding what you’re looking for, control-click (hold down the Control key on your keyboard and click) the app icon to reveal a list of that apps minimized windows. Choose an item from the list and it will open.
2/ Group windows by application in macOS Sierra — macOS Sierra introduced system wide tabs for most (but not all) apps, allowing you to merge multiple windows into a single window or separate merged windows.
With two or more windows of a supported app open, go to the Windows menu in the Finder and choose ‘Merge All Windows.’ All windows of the same app will be grouped into a single window. Each file you have open will appear as a tab inside the single window.
To separate the merged windows into standalone windows of their own, select the merged window to make it active. Go to the Windows and click the ‘Move Tab to New Window’ option. Click it to move the selected tab to a separate window.
This won’t separate all tabs into windows of their own, but separate the current tab to its own window. All remaining tabs will remain grouped into a single window unless you separate them one at a time.
Click the close button on a merged window, and it will close all tabs you have open in it.
3/ Move multiple Events between Calendars — If you’ve got several events you need to move to a different calendar, change to month view by pressing Command-3 or click on the Month option in Calendar’s toolbar or at top-centre of Calendar.
Now find the events you’d like to move, hold down Command on your keyboard and click on each one to select them all in turn.
When your events are all highlighted, right- or Control-click on any one of them. From the contextual menu that appears, choose the ‘Calendar’ option and pick the one you’d like to move your selected events to. Simple.
4/ Multiple ways to move items to Trash — Trash is a To put item(s) in the Trash, once can simply drag the item(s) to the Trash icon, or move highlighted file(s) to the Trash using the keyboard combo Command-Delete. If you realize you made a mistake, you can Undo the operation by choosing File > Undo, or the keyboard combo Command-Z.
If you’d like to delete highlighted items immediately, you can hold down Option and select File > Delete Immediately…. Alternately, you can use keyboard combo Command-Option-Delete. Either way, you’ll received a confirmation dialogue that the operation is permanent and can’t be undone.
5/ Empty stubborn Trash items — ToIf there are files in the Trash, which you can confirm visually because you’ll see items in the Trash, you can empty it by either choosing Finder > Empty Trash…, or using keyboard combo Shift-Cmd-Delete. You’ll be presented with a confirmation dialog asking if you’re sure. You can also hold down Option and select Finder > Empty Trash, or use keyboard combo Shift-Option-Command-Delete. Notice that since there isn’t a trailing ellipsis after the choice, it will be done immediately without a confirmation dialogue. [If this still doesnt work, you need Terminal, as detailed here.]