BertaWindowTools
BertaWindowTools is an independent Unreal Engine 5.8 Runtime plugin for inspecting and controlling the game window belonging to a supplied world context. It exposes a stateless C++ and Blueprint API and does not enumerate, accept handles for, or manipulate unrelated operating-system windows.
Installation
Copy the plugin into a UE 5.8 project's plugin directory:
BertaDevKitHost/Plugins/BertaWindowTools/
→ <YourProject>/Plugins/BertaWindowTools/
Build the project and enable BertaWindowTools. It is disabled by default, contains no third-party libraries, and has no dependency on another Berta plugin.
Target resolution and safety
Each call resolves WorldContextObject → UWorld → UGameInstance → UGameViewportClient → SWindow on demand. There is no subsystem, cached window pointer, global viewport fallback, tick, or lifecycle state. C++ calls must occur on the Game Thread; off-thread calls fail with OperationUnsupported instead of being queued.
In UE 5.8, UGameViewportClient::GetWindow() returns the SWindow containing the viewport. Embedded PIE can therefore resolve the main Unreal Editor window. Runtime APIs cannot reliably distinguish that window from a dedicated PIE window without an Editor dependency, so BertaWindowTools rejects all operations—including Get Game Window Info—when GIsEditor is true. The error is EmbeddedViewportUnsupported. Manual tests must use a separate-process Standalone game or a packaged build; PIE in New Editor Window is intentionally rejected as well.
Window information
Get Game Window Info returns FBertaWindowInfo:
| Field | Meaning |
|---|---|
Title |
Current window title. |
DesktopPosition |
Top-left of the outer window in virtual desktop pixels. |
WindowSize |
Outer window size in desktop pixels. |
ClientSize |
Drawable client-area size in pixels. |
DPIScale |
Native ratio of pixels to Slate units. |
WindowMode |
Unknown, Windowed, WindowedFullscreen, or Fullscreen. |
| State booleans | Visibility, Slate activity, native foreground, minimized, and maximized state. |
bHasDisplay, DisplayId |
Whether a monitor association was derived and its opaque UE ID. |
Coordinates share UE FDisplayMetrics virtual-desktop pixel space, so monitors left of the primary display retain negative coordinates. Client-size inputs are also pixels. UE 5.8's SWindow::Resize expects an already-DPI-scaled client size, so the plugin performs no additional Slate-unit conversion and avoids compounding DPI scale. For a minimized Win64 window, the reported outer rectangle is its meaningful restored geometry rather than Win32's possible iconic sentinel position.
UE's default Win64 game window uses a native OS border. Its cached SWindow position and size correspond to client geometry, while this API promises outer geometry. The implementation therefore uses a small private Win64 correction to read and move only the native window already resolved from the caller's GameInstance. All remaining behavior uses portable UE Runtime APIs, and no native handle crosses the plugin API.
Blueprint API
All nodes reset OutError and return a Success boolean.
| Node | Contract |
|---|---|
Get Game Window Info |
Resets and fills FBertaWindowInfo for the resolved game window. |
Set Window Position |
Moves the outer top-left to an absolute virtual-desktop pixel position. |
Set Window Client Size |
Requests a positive drawable size in pixels; project/platform constraints may clamp it. |
Center Window On Display |
Exact opaque display-ID match; centers in work area or full display rect. |
Center Window On Primary Display |
Finds UE's primary monitor and centers without requiring BertaSystemInfo. |
Maximize Window |
Issues the platform maximize request. |
Minimize Window |
Issues the platform minimize request. |
Restore Window |
Issues the platform restore request. |
Bring Window To Front |
Issues non-forced UE front/focus requests; a minimized window must be restored explicitly first. |
Set Window Title |
Sets the title through SWindow; empty text is allowed. |
Position, resize, and center operations require Windowed mode and a window that is neither minimized nor maximized. They return WindowNotWindowed or WindowNotRestored rather than silently changing mode or restoring. Maximize, minimize, and restore also reject fullscreen modes. Native state and focus transitions are requests: success does not guarantee synchronous completion or override operating-system foreground restrictions.
When centering, an outer window larger than the chosen destination area is placed at that area's top-left without being resized. Unknown IDs return DisplayNotFound; there is no primary-display fallback for an invalid ID.
Display interoperability
Display IDs are opaque UE FMonitorInfo::ID values and must not be parsed. BertaSystemInfo exposes the same native value in FBertaDisplayInfo::Id, so callers with both plugins installed can pass that field directly to Center Window On Display. This is optional semantic interoperability, not a module or plugin dependency.
For FBertaWindowInfo, the monitor with the greatest outer-window intersection area wins. Positive-overlap ties use UE's existing monitor order. With no overlap, the display rectangle nearest to the window center wins. With no monitor data, bHasDisplay remains false.
Deliberate limits and verification
BertaWindowTools does not create custom windows, control external windows, mutate topmost state, set window mode or resolution, apply UGameUserSettings, hide/show windows, change styles, confine the cursor, persist layouts, monitor hotplug, override DPI, or implement platform taskbar/tray behavior.
The repository verifies BertaDevKitHostEditor Win64 Development compilation. Runtime and packaged Win64 behavior and behavior on every other platform remain manual verification work; no all-platform runtime support is claimed.