On Thu, 18 Sep 2025 15:47:03 GMT, Martin Fox <[email protected]> wrote:
>> This PR fixes `isFocused()` returning invalid value when Stage fails to >> receive focus after calling `Stage.show()`. This problem is Windows-only. >> >> In Windows the `SetForegroundWindow()` API lists [a set of conditions to >> successfully grant focus to a >> Window](https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-setforegroundwindow#remarks). >> If any of the conditions are not met, the API will return FALSE. JavaFX did >> not respect that and instead assumed that receiving `WM_ACTIVATE` with our >> Window being activated is enough to assume the Window is in focus (which in >> some cases is not true). >> >> I first tried reacting to `WM_SETFOCUS` and `WM_KILLFOCUS` but it seems >> those messages are not sent when the window is shown for the first time >> (instead `WM_ACTIVATE` is used). >> >> To correct this behavior, I noticed the following path is the most reliable: >> - Call `ShowWindow()` using `SW_SHOWNA` instead of `SW_SHOW` - that makes >> the window visible but does NOT activate it >> - Call `SetForegroundWindow()` - that will attempt to give the Window focus >> and will also activate it if it is successful >> - If successful, Java `notifyFocus` callback will be called via >> `WM_ACTIVATE` handler >> - If it fails, we call the `notifyFocus` callback manually informing the >> upper layers the focus is lost. This establishes the correct state of >> `Window.focused` property. >> >> With this change I observed that all tests pass as intended as long as two >> conditions are met (these are needed to satisfy `SetForegroundWindow()` >> restrictions): >> - Gradle build is ran without the Gradle daemon >> - The terminal running Gradle test is in foreground >> >> If any of above two conditions is not met, some tests (including canary test >> from https://github.com/openjdk/jfx/pull/1804) now timeout/fail when >> checking whether `Window.isFocused()` is true. >> >> Manually started JavaFX apps (ex. Ensemble) run as they used to and still >> receive focus upon Stage showing. > > I’ve been testing this PR by launching the manual KeyboardTest app. > > java @build/run.args tests/manual/events/KeyboardTest.java > > The call to SetForegroundWindow fails but not before activating the window. > Since it’s not the foreground window this PR correctly sets the JavaFX > focused property back to false. But when I later click on the title bar to > bring the window to the foreground the focused property is not updated. > > I’m not sure how we’re expected to detect that our HWND has come to the > foreground. There’s no specific message sent when this happens and since the > OS thinks the window is already active and focused we don’t get WM_ACTIVATE > or WM_SETFOCUS. There’s some messages we could use heuristically (like > WM_NCACTIVATE) but I couldn’t find anything more clear cut. I'll keep looking > but it doesn't look like Windows makes this easy. Reviewers: @beldenfox @kevinrushforth ------------- PR Comment: https://git.openjdk.org/jfx/pull/1849#issuecomment-3462804291
