When points are drawn via the device pipline [DrawPrimitive(D3DPT_POINTLIST, ...)] in a swapchain, the shape of the point takes a shape (rectangular vs square) according to the aspect ratio of the swapchain view window. Other shapes drawn via the pipleline (mesh->DrawSubset) and via a shader (effect) appear correctly. The points exhibit that behavior whether drawn in pixels or world units.
In the image below, all three views are separate swapchain child windows of the main window. Note the sphere (ID3DXMesh) is not distorted (nor are other objects). The points, as can be seen, seem to appear with the aspect ratio of the view window. Shown here, the points are being drawn in world units.
Also shown in wireframe fillmode, the appearance is the same in solidfill.
As I'm (unsuccessfully) trying to figure out mesh picking in swapchain views, it appears that the points, when being rendered, are affected by the aspect ratio of the window associated with the swapchain, whereas other objects are not.
If it's important: I've tried it with hardware and software vertex processing, and with swapeffect = discard and = copy.
Anyone have an explanation? Is this a bug perhaps?