Crash dropping html on Windows Tcl 9

[apnadkarni]

To reproduce from the demos directory, in wish90

package require tkdnd
source simple_target.tcl
source simple_source.tcl

Drag from the HTML label to the drop widget. A memory access violation is generated.

Building against Tcl 8.6 works fine.

[apnadkarni]

PR #68 is a proposed fix. Note this addresses the crash resulting from any error retrieving the global handle.

The underlying root cause of the error - mismatched encodings between Tcl 9 Tcl_UniChar and Windows WCHAR for HTML data - is not addressed here. Working on that separately...

[petasis]

PR #68 has been merged. Can you please test it?

[apnadkarni]

Verified demos with VS 2022 x64 using win/makefile.vc against 8.6.10 and 9.0.0. Note I don't use tkdnd so I do not have a specific application test. The original report was also based on demos.