#1527 cursor incompatabilities

[Pat Thoyts]

Originally submitted as a Tcl FR by rox - moved to Tk.

the native pointer in X is "left_ptr" and in windows is
"arrow". i suggest remapping the cursors so that arrow
is the native pointer on all platforms

the fleur/move cursor does not have the native
appearance in windows

there is no native hand (hyperlink) cursor spec in
windows. it should be easy to add a mapping for hand2
to IDC_HAND.

the documentation says the "size" cursor is available
in windows but i got an error when trying to use it in
my 8.4.2 tclkit.

all X cursors are available under windows as tk has
them built in. however the windows cursors are not
available on other platforms which can cause errors. i
would suggest mapping the windows cursor names to their
similar X names when running in X.

[Pat Thoyts]

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The hand cursor can be implemented by defining hand to match
IDC_HAND. This token isn't defined unless WINVER >= 0x0500
but I've found that we can set the resource manually and if
it isn't found at runtime, then we will default to the Tk
unix-style hand cursor.

The IDC_SIZE cursor is documented as depreciated and we
should be using IDC_SIZEALL. This deals with the fleur and
size cursor problems listed above.

[Pat Thoyts]

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Committed fixes for the hand2 cursor and to fix the size and
fleur cursors. I've also added tests to ensure than all the
documented cursors are actually available for each platform.

I think that for portability Tk apps should restrict
themselves to the unix defined set of cursors. I'll leave
this open for a bit for comments about the default cursor
name and if the same set of names should be available
everywhere.

[Pat Thoyts]

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Backported the Windows cursor changes from Tk 8.5 to 8.4 branch.