This is the mode in which you will do all of your user interface design. You can switch to the Design mode using the Design button on the left part of the Qt Creator screen. Note that if this button is grayed out, which means it is inactive, then you need to select a user interface file (*.ui) first, because only ui files can be opened using the Designer. To do this, you can double-click on the mainwindow.ui file in the left pane (Projects pane):
The Design mode contains all the tools required from a powerful GUI designer. It has a WYSIWYG (what you see is what you get) type of GUI editor that allows adding, removing, editing, ...
