Windows

Content draws in native windows made with new DesktopEngine.Window({ type }).

type	For
desktop	Wallpapers: the desktop level, below the desktop icons, on all Spaces, and it gets mouse moves
widget	Widgets on the desktop: above the desktop icons, borderless with a clear background, can be dragged
overlay	Above all windows: borderless with a clear background, on all Spaces and over full screen apps; for floating widgets and desktop pets
panel	A floating panel with a title bar
normal	A standard window

Showing a desktop, widget or overlay window doesn't activate DesktopEngine, so it doesn't take the focus from the user's current app.

The content's type decides which windows it can create, and the runtime enforces it: wallpapers only desktop; widgets and desktop pets only widget and overlay (where the user put it: pass launchOptions.windowType). Any other type, including a standard window without type, makes new DesktopEngine.Window() throw. Content from desktopengine dev and the Develop menu is held to the same rules, so you find out before you ship; mini programs without a manifest aren't.

Windows are transparent and their styles have no corner radius: to round the corners, draw a rounded rectangle on a canvas (see the widget template). A window stays until you call destroy().

Mouse

• Pressing anywhere in a widget or overlay window drags it (the system's own window dragging): a drag gets mousedown, the window's move, and mouseup on release, with no mousemove during the drag; a click only gets click, no mousedown / mouseup.
• The window's dragRegion limits where a press drags the window; elsewhere presses and drags go to the components (mousedown, mousemove while the button is down, mouseup), for controls such as dials and sliders. null (the default) is the whole window, [] nowhere.
• A window dropped on a screen edge keeps its size and stays where it was dropped, though macOS still shows where it would tile it. Set the window's allowsTiling to true to let macOS tile it, e.g. to half the screen, and handle resize.
• The window's hitRegion (an array of rectangles in points from the window's top left corner) limits the mouse to those parts: clicks, drags and hovers elsewhere pass through to the windows below. null (the default) is the whole window. Transparent parts of a window still catch the mouse by default, so an irregularly shaped pet should update it as it draws (see the pet template).
• mouseenter, mousemove and mouseleave fire even when the window isn't the key window.
• Event callbacks get plain objects, and this is the object that fired the event; the double click event is named dbclick.

Displays and scale

• launchOptions.display is the display the content is on: frame is the whole screen, visibleFrame leaves out the menu bar and the Dock.
• A window's devicePixelRatio is the scale of its display. When a widget or pet is dragged to a display with another scale (from a Retina screen to a 1x external display, say), or the user changes the display's resolution, it changes and the window fires devicepixelratiochange: set the canvas's width / height for the new value and redraw.
• Unlike in browsers, setting width / height here doesn't reset the 2D context's state: set the scale with setTransform(ratio, 0, 0, ratio, 0, 0) rather than adding another scale() (see the widget and pet templates).

See Window for all its properties and events.