The easiest way to make a small selection is to click and drag with the mouse. But this method is tedious if you want to select a very large piece of text.
In EditPad Lite and Pro, you can expand a selection by keeping the Shift button depressed while clicking with the mouse. If there was no selection yet, the text between the text cursor and the spot where you Shift+clicked will be selected. If you Shift+clicked outside the selection, the text between the selection and the click spot will be added to the selection. If you Shift+clicked inside the selection, the selection will be reduced.
To make a medium sized selection, click on the spot where you want to start it. Then scroll the text as needed, and Shift+click where the selection must end.
EditPad Pro provides two commands with corresponding keyboard shortcuts to make it easy to select even larger blocks of text. Block|Begin Selection marks the current position of the text cursor as the start of a new selection. Block|End Selection selects the text between the position where Begin Selection was used, and the current position of the text cursor.
To select a very large block of text, first navigate to the position where the selection should start, and use Block|Begin Selection. Then use whichever way you want, such as the go to line command or a search to find the place where the selection should end. It's perfectly fine if some text becomes selected or deselected while you do this. Put the text cursor at the position where you want to end the selection, and choose Block|End Selection from the menu. This selects the text between the "Begin Selection" and "End Selection" spots, irrespective of what you did in between.
You can use the same methods to select text in the edit boxes in AceText, PowerGREP or RegexBuddy as they are all based on the EditPad text editor control. They do not have the "Begin Selection and "End Selection" menu items. Use the Ctrl+Shift+B and Ctrl+Shift+E keyboard shortcuts instead.