"colored" overlay

[ebachard]

First, thanks a lot for your tabs, they are working very well on my side, excepted one issue I think I found the why (maybe my fix is just a bad hack, please apologies).

To reproduce the issue, have a look at the screenshot I provived in ocornut/imgui#1083 : just below the active tab, "Aide", you'll see the white ( alpha = 0.15) background. The problem is that this background is drawn on top of the tabs contents (sort of "overlay"), and e.g. when one tab is a frame coming from a webcam, the colors are plain wrong. This issue is true for every tab in fact.

Second issue (linked) : when you move the window containing the tabs, or resize it, the background is modified, means probably does not use the right coordinates. This should be fixed too in the proposed code.

As workaround, I modified your code to draw the background before to fill it with the content.

Please see the commit I did there : https://github.com/ebachard/imgui_tabs

Last but not least, I'll attach a screenshot with what I got now.

Feel free to use the proposed code under the license you prefer, that's no problem for me ;-)