Mnemonics and Accelerators
Gtk+ provides two means of creating "hot-keys" for keyboard operation of menu items and controls: Accelerators and special labels called mnemonics.
Accelerators are normally assigned only to menu items, but they can be assigned to any control using a GtkAccelLabel. "Can" does not mean "should"! Pressing the character together with the configured modifiers calls whatever function is linked to the control. Accelerators can be over-ridden by users using an accelerator map. Accelerators can be set in GtkBuilder/Glade files using the
- MacOS Note
- In most cases MacOS prefers the <command> key to the <control> key as a modifier. Gtk provides a macro
GDK_MODIFIER_INTENT_PRIMARY_ACCELERATORthat selects the correct modifier depending on OS. It should be used in most cases rather than
GDK_CONTROL_MASK. As noted below under Mnemonics MacOS uses the <alt> modifier key to extend the keyboard, so it should be used only with another not-<shift> modifier key in accelerators. Note that on MacOS GDK_MOD2_MASK is the <command> key while on X11 it's <numlock> so either one must conditionally set accelerator modifiers (not possible in Glade), rely on an accelerator map to get a useable accelerator set, or restrict the modifiers to <control><alt> and <code.GDK_MODIFIER_INTENT_PRIMARY_ACCELERATOR</code>. Unfortunately Glade does not support GdkModifierIntent and Gtk+ has supported it in GtkBuilder files only since 3.20 so it can be used only in accelerators defined in code.
GtkShortcutsWindow is a convenient way to display all of GnuCash's accelerators to the user. Unfortunately it wasn't introduced until Gtk+-3.20.0 and we want to support Gtk+-3.10 and later, so don't implement it.
Mnemonics can be set on menu items as well as buttons or indeed any control by attaching it to the relevant label. However one should be aware that menu-item mnemonics work quite differently: Mnemonics on controls operate like accelerators: Holding <alt> will reveal underlines on the mnemonic characters for the focused window or dialog and pressing an underlined character will operate the respective control. If the focused window has a menu bar associated with it the menu bar will be revealed if it's hidden and the mnemonics will be shown; pressing the mnemonic for a menu bar item will open that menu. At this point the <alt> can be released and the menu navigated by pressing the mnemonic keys alone. In addition to the linked functions, mnemonics can be set in GtkBuilder/Glade files with the
use_underline and (on GtkLabels, not needed for GtkButtons)
- Mnemonics have two problems on Macs
- First, they don't work on the menu. Keyboard menu navigation is accomplished by pressing <ctrl>F2 (don't forget to also press <fn> on keyboards that use one unless you've flipped the <fn> key behavior in Keyboard Preferences) to activate the menubar and then navigating with the cursor keys. Second, MacOS used the <alt> key to extend the keyboard; for example on a US keyboard one would type <alt>e e to get é or <alt>o to get ø. Setting a mnemonic will grab the event before the text control gets it and prevent that character from being typed.
Note that when one creates a mnemonic with an underscore the underscore becomes part of the label string that is a msgid for translation, so the same label with different mnemonics will result in multiple strings for translation. This is a good thing because it allows translators to select appropriate mnemonics for their languages.
Menus should have a mnemonic in their label and they should have a tooltip. If they call a dialog (or assistent) the label should have a trailing horizontal ellipse
Tooltips and dconf Descriptions
Tooltips should contain at least one full sentence.
Tooltips of preferences have usually 3 occurences:
- glade: Edit->Preferences->...
<property name="tooltip_text" translatable="yes">your text</property>
- gschema (xml):
- gnucash-help/custom-gnucash... (docbook xml):
<listitem> <para><guilabel>Include grand total:</guilabel> If checked, show in the <emphasis>Summarybar</emphasis> a grand total of all accounts converted to the default currency.</para> </listitem>
Use for all the same text to keep it simple for translators. They should not feel like in the colossal cave adventure:
You are in a maze of twisty little passages, all alike. You are in a maze of twisty little passages, all different. You are in a little maze of twisty passages, all different. You are in a little maze of twisting passages, all different. :