You already know how to add and move widgets in the Design mode. Now, we need to make the UI neat and tidy. I'll show you how to do this step by step.
A quick way to delete a widget is to select it and press the Delete button. Meanwhile, some widgets, such as the menu bar, status bar, and toolbar can't be selected, so we have to right-click on them in Object Inspector and delete them. Since they are useless in this example, it's safe to remove them and we can do this for good.
Okay, let's understand what needs to be done after the removal. You may want to keep all these push buttons on the same horizontal axis. To do this, perform the following steps: