Сlickthrough and Transparent background viewport

[lavrentijav]

Feature Request: Clickthrough Viewport Background with Transparency and Mouse Support

Is your feature request related to a problem? Please describe.

I'm often frustrated when I need to create a Dear PyGui application with a transparent viewport background that allows interaction with underlying applications (clickthrough) while still enabling mouse interactions with Dear PyGui windows. Currently, setting the viewport background to transparent (e.g., dpg.set_viewport_clear_color([0, 0, 0, 0])) results in a black background instead of true transparency, and there’s no built-in support for clickthrough behavior, forcing me to choose between a fully interactive viewport or a completely non-interactive one. This limits the ability to create overlay-like interfaces where the viewport background is invisible and clickthrough, but Dear PyGui windows remain fully interactive.

Describe the solution you'd like

I’d like the ability to:

1. Set the viewport background to be fully transparent (alpha channel = 0) so it blends seamlessly with the desktop or applications behind it.
2. Enable clickthrough behavior for the transparent viewport background, allowing mouse clicks to pass through to underlying applications.
3. Retain full mouse interaction (clicks, hovers, etc.) for Dear PyGui windows within the viewport, ensuring they function normally.

This could be implemented via new viewport configuration options, such as:

• dpg.set_viewport_transparency(True) to enable true transparency.
• dpg.set_viewport_clickthrough(True) to allow clicks to pass through the transparent background but not the Dear PyGui windows.

For example:

import dearpygui.dearpygui as dpg
dpg.create_context()
dpg.create_viewport(title="Transparent App", width=800, height=600)
dpg.set_viewport_transparency(True)  # Make viewport background fully transparent
dpg.set_viewport_clickthrough(True)  # Clicks pass through transparent areas
with dpg.window(label="Interactive Window", width=200, height=200):
    dpg.add_button(label="Click Me")  # Window remains interactive
dpg.setup_dearpygui()
dpg.show_viewport()
dpg.start_dearpygui()
dpg.destroy_context()

Describe alternatives you've considered

1. Using C# ImGui with Clickable Transparent Overlay: In C# ImGui, a package like "clickable transparent overlay" achieves this behavior by creating an invisible viewport while keeping ImGui windows interactive. However, this requires switching to C#, which I’d prefer to avoid as I’m more comfortable with Python and Dear PyGui.
2. Custom Window Styling: I tried setting the viewport’s clear color to [0, 0, 0, 0] and adjusting window themes to minimize the background, but this doesn’t achieve true transparency or clickthrough behavior. It also doesn’t allow mouse events to pass through the viewport.
3. No Title Bar and Custom Windows: I considered using no_title_bar=True and no_background=True for windows to simulate a floating interface, but this doesn’t address viewport transparency or clickthrough for the background, and managing multiple windows this way is cumbersome.
4. External Libraries: I explored using other Python GUI frameworks like PyQt or Tkinter, but they either lack the GPU-accelerated performance of Dear PyGui or have more complex APIs for achieving transparency and clickthrough, making Dear PyGui a better fit if this feature is added.

Additional context

This feature would be highly valuable for creating overlay applications, such as desktop widgets, annotation tools, or HUD-like interfaces, where the viewport background needs to be invisible and non-blocking, but the Dear PyGui windows remain fully functional. Similar functionality exists in C# ImGui, suggesting it’s feasible to implement in Dear PyGui, possibly by leveraging the underlying Dear ImGui or OS-specific windowing APIs (e.g., Win32, Metal, or Vulkan). Existing GitHub issues ( #1142 ) indicate community interest in viewport transparency, but they don’t fully address clickthrough or mouse interaction with windows, so this request extends those ideas. A potential challenge might be OS-specific behavior (e.g., Windows vs. macOS), but a unified API with fallbacks (e.g., partial transparency if full clickthrough isn’t supported) would still be useful.