SC inconsistent behaviour when capturing a "blank" window.

[IainB]

I thought I would mention this as a point of interest. It's not a bug (that is, I don't think it's bug).

I was playing about with T-Clock settings in the Miscellaneous tab of T-Clock Redux Properties and setting it to display a calendar window.
One of the settings was - I think - selected (ticked) by default: "Close calendar on lose focus". I left that setting selected, as it seemed like a useful option.
I then brought up the Calendar window, intending to take a screenshot of it using SC.
I then brought up SC, and noticed that the Calendar window disappeared as it lost focus (so the option was working correctly).

So, I got SC to display its Quick-Capture bar, and then brought up the Calendar window again.
When I clicked on the Quick-Capture bar's "Grab Active window" button, the Calendar window went black, there was a delay, the Calendar window disappeared, and there was a "ping" alarm sound. After Ctrl-Tabbing about, I found that SC had output the following error message in a new window in the back, behind the other windows (i.e., not On Top):

---------------------------
Error Capturing Image
---------------------------
ERROR: No content was found in the captured image.
This can happen if you have installed a security application that is blocking Screenshot Captor from functioning.
To solve this problem, you may need to add Screenshot Captor to the list of trusted/allowed programs in your security application.
For additional information see the help file or visit the DonationCoder.com forum.
If you were intentionally capturing a blank image, disable this check on the Miscelaneous Tweaks tab of options.
---------------------------
OK   
---------------------------

So, I brought up the Calendar window again.
Then I pressed Alt+PRTSC, and the Calendar window went black, there was a delay, the Calendar window disappeared, and there was a "camera shutter" sound. In the SC work area, SC had captured an entirely blank image of the calendar window.

These steps are all repeatable and with consistent results.

Since I could not capture the Calendar window using SC, I resorted to capturing it using the OneNote Screen Clipping tool (via a hotkey combo) - which worked just fine, though it is not as good as using SC because the OneNote tool has an on-screen rectangle which has to be manually dragged and sized by one corner only, around the window being captured, and it is difficult to get it spot-on.

[mouser]

When you ask SC to capture the active window (Alt+PrtScr) instead of the whole screen or select a region, it tries to use an elaborate mechanism to capture semi-transparent border areas found in newer version of windows; this is how SC can nicely capture curved corners on windows.  That process causes a flash of black and white behind windows when you do such captures.

There may be some apps which for some reason don't react well to such attempts -- i can't say for sure why, though it may be because they dont respond to repaint messages.

Anyway, one fix is simply to capture the entire screen and then crop from within SC, which should have already selected the active window region so you only have to press crop button.

The other alternative is to tell SC to not try to capture transparency for windows (see Widow Capturing tabs in options).  This will have the benefit of making active window captures faster.

Let me know if that solves your problem.

[IainB]

Ah, I see.
Hmm...grabbing the whole screen and then cutting out just the bit I wanted seems like it would be taking a step backwards rather than forwards, but the option "tell SC to not try to capture transparency for windows (see Widow Capturing tabs in options)" looked useful, so I tried that by unticking the "Try to capture Aeroglass transparency effects" and:
(a) by clicking on the Quick-Capture bar's "Grab Active window" button.
     Result: SC did not capture the window.

(b) by pressing the Alt+PRTSC hotkey combo.
     Result: there was no delay, and SC captured the Calendar window, but with a light blue coloured
     border whereas the on-screen window was a light brown colour.

Which is a good outcome in (b), though I have no idea why (a) did not give a result consistent with (b).
It was a similar inconsistency that I first thought I'd let you know about in the OP above.