When running the Tk testsuite against Tcl 9.0, there are 3 test-failures:

See: [https://github.com/tcltk/tk/actions/runs/5000425737/jobs/8962784135]

But the build with 8.7 and 9.1 (unofficial) is OK. This points to a problem in the current trunk, not actually in Tk:

<pre>
imgPhoto.test


==== imgPhoto-4.79 ImgPhotoCmd, transparency get: no option FAILED
==== Contents of test case:

    set pixelCoords {{156 239} {76 207} {153 213} {139 43} {75 112}}
    foreach coord $pixelCoords {
	lappend result [photo1 transparency get {*}$coord]
    }
    set result

---- Test generated error; Return code was: 1
---- Return code should have been one of: 0 2
---- errorInfo: can't read "coord": no such variable
    while executing
"photo1 transparency get {*}$coord"
    ("foreach" body line 2)
    invoked from within
"foreach coord $pixelCoords {
	lappend result [photo1 transparency get {*}$coord]
    }"
    ("uplevel" body line 3)
    invoked from within
"uplevel 1 $script"
---- errorCode: TCL LOOKUP VARNAME coord
==== imgPhoto-4.79 FAILED



==== imgPhoto-4.81 ImgPhotoCmd, transparency get: -alpha FAILED
==== Contents of test case:

    set pixelCoords {{156 239} {76 207} {153 213} {139 43} {75 112}}
    foreach coord $pixelCoords {
	lappend result [photo1 transparency get {*}$coord -alpha]
    }
    set result

---- Test generated error; Return code was: 1
---- Return code should have been one of: 0 2
---- errorInfo: can't read "coord": no such variable
    while executing
"photo1 transparency get {*}$coord -alpha"
    ("foreach" body line 2)
    invoked from within
"foreach coord $pixelCoords {
	lappend result [photo1 transparency get {*}$coord -alpha]
    }"
    ("uplevel" body line 3)
    invoked from within
"uplevel 1 $script"
---- errorCode: TCL LOOKUP VARNAME coord
==== imgPhoto-4.81 FAILED

imgSVGnano.test
listbox.test
main.test
menu.test
menuDraw.test
menubut.test
message.test
msgbox.test
obj.test
oldpack.test
option.test
pack.test
packgrid.test
panedwindow.test


==== panedwindow-17.1 MoveSash, move right FAILED
==== Contents of test case:

    panedwindow .p -showhandle false -borderwidth 0 -sashpad 0 -sashwidth 2
    foreach w {.f1 .f2} c {red blue} {
        .p add [frame $w -height 20 -width 20 -bg $c] -sticky nsew
    }

    # Get the requested width of the paned window
    lappend result [winfo reqwidth .p]

    .p sash place 0 30 0

    # Get the reqwidth again, to make sure it hasn't changed
    lappend result [winfo reqwidth .p]

    # Check that the sash moved
    lappend result [.p sash coord 0]

---- Test generated error; Return code was: 1
---- Return code should have been one of: 0 2
---- errorInfo: unknown color name "3"
    (processing "-bg" option)
    invoked from within
"frame $w -height 20 -width 20 -bg $c"
    ("foreach" body line 2)
    invoked from within
"foreach w {.f1 .f2} c {red blue} {
        .p add [frame $w -height 20 -width 20 -bg $c] -sticky nsew
    }"
    ("uplevel" body line 3)
    invoked from within
"uplevel 1 $script"
---- errorCode: TK LOOKUP COLOR 3
==== panedwindow-17.1 FAILED

pkgconfig.test
...
</pre>

Looking at the build history, this build was done using Tcl commit [427bc951fbcffe81], which the previous successfull build was done using Tcl commit [8181a7f089ec83e0].

There are 3 suspicious commits in this range:

* [427bc951fbcffe81] Fix memory leaks and remove unnecessary reference count bounce.

* [40af0258ecad67cd] New function, TclDuplicatePureObj(), ....

* [0785828c472b53ea] Add Tcl_DecrRefCount() missing from [4b1a20629e].

Which of those 3 commit's is the coolpit, I don't know.