Fix desktop launch, app icons and keyboard parameter editing

docs/book/src/guide/parameters.md

@@ -9,6 +9,12 @@ In the SOLID toolbar's CONFIGURE panel, click **Parameters** to open the user an
 parameter editor. The separate **Configurations** button opens the configuration table;
 **Configure** remains in the dropdown for configuring columns.
 
+Press **Enter** in the new parameter's name, expression or comment field to add it.
+Valid entries return focus to the name field for the next parameter; invalid entries remain
+editable. In expression fields, **Up/Down** selects an autocomplete suggestion,
+**Enter/Tab** accepts it, and **Escape** dismisses the suggestions. Accepting a suggestion
+does not also submit the parameter.
+
 Expressions are unit-aware: `2 * width + 5 mm`, `angle / 2`, `sqrt(area)`, `1 in + 3 mm`, using
 `+ - * / ^`, parentheses, `sin cos tan asin acos atan atan2 sqrt abs min max floor ceil round mod
 trunc` and unit conversion. A length where an angle is expected (or the other way round) is an