select workspace and press Ctrl–H
Which dialog is selected, depends on which file type is selected in the Project Explorer view. For example, if you selected a .js file and press Ctrl–H, it will bring up the dialog with the “Javascript Search” tab selected. If you want to search all files, you can press Ctrl–F7 to select the Project Explorer view, use arrow keys to select a folder above your files, then press Ctrl–H (or select a file, whose type doesn’t trigger a custom dialog tab).