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Menu Selection and Accelerators

Menus from the main menu bar are displayed when the left mouse button (button 1) is pressed over a menu bar entry. The drop-down listing of entries will appear. A selection can be made by releasing the mouse button over the item to be selected. Alternatively, clicking the mouse button will also cause the menu to appear, and clicking over the menu will select the item under the pointer, and retire the menu. While the menu is visible, keypresses are ``grabbed'' by the menu, and so will not be sent to other windows or applications. While a menu is visible, the up and down arrow keys will cycle through the menu entries, highlighting each in sequence. Pressing Enter will ``press'' the highlighted entry. The entries in the side menu are mostly toggle buttons, which are activated by clicking with mouse button 1.

Commands can also be executed by typing an accelerator while the mouse pointer is in a drawing window. Commands can be exited by selecting another command in most cases, or by pressing the Esc key. Some commands are switches which remain in effect until selected again.

There are multiple accelerator functions available.

  1. Alt-char brings up the menu keyed by char where char is the character that is underlined in the name in the menubar. If this is followed by a character underlined in one of the menu entries, that function is invoked. For example, typing Alt-fp (press and hold Alt, press f, release Alt, press p) engages the Print command in the File Menu.
  2. If the menu entry has something in the second column, that is also an accelerator. For example, in the File Menu, the Quit entry has ``Ctrl-Q'' listed in the second column. This indicates that pressing Ctrl-q will invoke the Quit command. The menu doesn't have to be visible.

    Under Unix/Linux, the menu accelerators can be changed interactively. Click on a menu to open it, then move the pointer over one of the entries (it will be highlighted). Pressing Shift, Ctrl or Alt along with another key will add that accelerator to the menu entry, or change an existing accelerator. With the menu invisible, entering that key combination will ``press'' the assigned button, unless the combination happens to be used elsewhere for another purpose (it must be unique in the menus, at least). Under Windows, the menu accelerators can not be changed.

  3. Every command has a name, shown in the tooltip bubble that appears after the pointer is stationary over the button for a second or two. Typing the first few characters of this name will trigger that command. Only the characters required to uniquely specify the command name among all commands currently is scope are required. When activated, the name of the command is printed in the key press buffer window. For example, ``pus'' triggers Push.
  4. One can define macros for keypress combinations with the Define Macro command button in the Attributes Menu.


next up previous contents index
Next: Keyboard Input Up: Graphical Interface, Commands and Previous: Quoting   Contents   Index
Stephen R. Whiteley 2017-10-02