Today, test_TxGetNaturalSize() creates a pop-up window with a fixed size (extent) of 100 x 100. The test function then proceeds to compute the natural size of rich edit control that fits the sample text "TestSomeText" and compare it to the RECT calculated by DrawText.
It appears that this test fails if the text width exceeds the width of the test window's client area. In this case, DrawText() with DT_WORDBREAK breaks the text into the two lines due to text wrapping; however, Rich Edit's ITextServices::TxGetNaturalSize implementation does not seem to perform text wrapping on overflow. This results in extent mismatch.
In conclusion, the test may fail if the rendered width of the sample text "TestSomeText" is larger than what the test expects. This depends on the current font used for DEFAULT_GUI_FONT.
Fix this by omitting the DT_WORDBREAK flag for the DrawText() call in _check_txgetnaturalsize().
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=54637
-- v2: riched20/tests: Don't specify DT_WORDBREAK in _check_txgetnaturalsize().