Press Ctrl+Q while the cursor is on a symbol to reveal the Quick Documentation pop-up window and display the symbol’s corresponding documentation. Press Esc to dismiss the pop-up window.
For built-in PHP symbols press Shift+F1 to open the documentation for the symbol on php.net in a web browser.
These actions can also be found in the menus: - View | Quick Documentation Lookup - View | External documentation
Press F1 to show the Quick Documentation pop-up window.
Press Shift+F1 to open the external documentation.