Common methods for all Controls

All controls (including Window and Desktop) have a set of common methods obtained via the Deref trait over a common base object.

Method	Purpose
`set_visible(...)`	Shows or hides a control (has no effect on a Desktop)
`is_visible()`	Returns true if the current control is visible, or false otherwise
`set_enable(...)`	Changes the enable/disable status of a control (has no effect on a Window or a Desktop control)
`is_enabled()`	Returns true if the current control is enabled, or false otherwise
`has_focus()`	Returns true if the current control has focus, or false otherwise
`can_receive_input()`	Returns true if the current control could receive mouse or keyboard events if focused or false otherwise
`is_mouse_over()`	Returns true if the mouse cursor is over the current control

Method	Purpose
`size()`	Returns the size (widthxheight) for the current control
`client_size()`	Returns the client size (the size minus the margins) for the current control
`set_size(...)`	Sets the new size for a control (to a specified size given by parameters `width` and `height`). Keep in mind that this method will change the existing layout to a layout based on the top-left corner (given by the control's `x` and `y` coordinates) and the newly provided size. Any dock or alignment properties will be removed. This method has no effect on a Desktop control.
`position()`	Returns the relative position (x,y) of the current control to its parent.
`set_position(...)`	Sets the new position for a control (to specified coordinates given by parameters `x` and `y`). Keep in mind that this method will change the existing layout to a layout based on the top-left corner (given by coordinates `x` and `y`) and the control's current width and height. Any dock or alignment properties will be removed. This method has no effect on a Desktop control.
`set_components_toolbar_margins(...)`	Sets the left and top components margins - for scrollbars, filters, etc
`update_layout(...)`	Updates the layout of a control

Method	Purpose
`hotkey()`	Returns the hotkey associated with a control, or `Key::None` otherwise
`set_hotkey()`	Sets the hotkey for a control. To clear the hotkey call this function like this: `.set_hotkey(Key::None)`

Update methods

Method	Purpose
`request_focus()`	Request the framework to assign the focus to the current control
`request_update()`	Request the framework to update itself. This action will update the command bar, menus, and the positions of the controls.

Method	Purpose
`register_menu(...)`	Registers a menu in the `AppCUI` framework and returns a handle for it
`show_menu(...)`	Show a popup menu that was registered by the current control
`menuitem(...)`	Returns an immutable reference to a menu item based on two handles: one for the menu, and one for the menu item
`menuitem_mut(...)`	Returns a mutable reference to a menu item based on two handles: one for the menu, and one for the menu item

Method	Purpose
`theme()`	Returns a reference to the theme object that is being used by the application. This is the same reference an object receives when the `OnPaint` method is called.

Method	Purpose
`appbar()`	Returns a reference to the application bar object that is being used by the application. This method will panic if the application bar is not enabled (via the `app_bar()` method when building the application)