RFR: JDK-8313628: Column drag header, overlay and line are not correctly aligned

[Marius Hanl]

On Wed, 2 Aug 2023 16:36:47 GMT, Marius Hanl <mhanl at openjdk.org> wrote:

> When a table has padding or the `layoutChildren` method inside the table skin is overridden (and x/y are modified), the drag drag header, column overlay and column line are not correctly aligned.
> 
> The reason is that the positions were calculated incorrectly.
> - **Column overlay and column line**
> Always calculate in the x and y from the table. The x and y variables contain the snapped insets (padding) and possible modifications from subclasses.
> - **Drag header**
> Calculate the drag x offset local bounds from the parent header (which is either the parent column header or the root header)
> Before, the local bounds were calculated from the table, which will wrongly calculate in the padding.
> We do not want to know the local bounds based of the whole table but of our header we are in.

modules/javafx.controls/src/test/java/test/javafx/scene/control/skin/TableViewSkinTest.java line 69:

> 67:         scene.getStylesheets().add(TableViewSkinTest.class.getResource("TableViewSkinTest.css").toExternalForm());
> 68: 
> 69:         stageLoader = new StageLoader(scene);

Note: I just cleaned up this test to also use the more safe `stageLoader` approach.
Unfortunately the diff looks a bit weird...

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PR Review Comment: https://git.openjdk.org/jfx/pull/1193#discussion_r1282168787