Merge pull request #1538 from ndandoulakis/ndandoulakis-CS_DBLCLKS-patch ...

Examples: DirectX9,10,10: Support for CS_DBLCLKS by treating double-click down messages are regular down. (#1538, #754)

Examples: Using IM_OFFSETOF macro. + Comments

CS_DBLCLKS support for DirectX 11

CS_DBLCLKS support for DirectX 10

CS_DBLCLKS support for Directx9

Examples: Visual Studio projects: Disabled extraneous function-level check in Release build.

Examples: Comments about invalid mouse pos.

Examples: DirectX10,DirectX11: Moved call to OMSetRenderTargets() in main loop so example code can integrate more nicely with other code.

Examples: Vulkan: Tweak

Examples: Comments, synched some minor drift between examples + stronger suggestion to use StyleColorsDark().

Renamed the emblematic ShowTestWindow() function to ShowDemoWindow(). Kept redirection function (will obsolete).

Examples: DirectX: Using IM_ARRAYSIZE()

Examples: Added null_example/ which is helpful for quick testing on multiple compilers/settings without relyong on graphics library.

Examples: DirectX9: Call EndFrame(), fix for assert added in 9a44d44

Examples: DirectX9: Handle loss of D3D9 device (D3DERR_DEVICELOST). (#1464)

Horizontal mouse wheel support ...

This patch adds support for the horizontal mouse wheel in ImGui. It
affects windows that can be scrolled, as long as the Ctrl key is not
being pressed.

The scrolling speed has been set empirically so that it matches the
scrolling speed on the Firefox browser when the horizontal wheel is
used.

Internally, it adds a MouseHorizWheel to ImGuiIO, which is then used in
NewFrame to scroll the current window.

The SDL/GL2, SDL/GL3, GLFW/GL2 and GLFW/GL3 examples has been modified
to use it.

Sisyphus says: tweaked comments about not using old-style OpenGL examples (#1459, #1394 etc.)

Sisyphus says: tweaked comments about not using old-style OpenGL examples (#1459, #1394 etc.)

Fix wrong comment in dx implementation headers

Examples: Added a bunch of comments/referencs related to io.WantCaptureMouse, io.WantCaptureKeyboard (#1262, #1237, #1219, #635, #1058, #1051, #912, #533, #703, #446, #459, #364, #213, #52, and more)

Examples: Comments to guide people unfamiliar with the librairies used.

Examples: Added more comments near the fonts loading section, to catch common questions and errors (e.g. #1397, #1366, #1341, #1222, #1193, #1115, #951, etc.)

Examples: Extra clarification for the 100th person who insist on using the OpenGL2 code in spite of existing documentation leaning against it. (#1394)

Examples: DirectX9/10/11: Tweak usage of SetCapture/ReleaseCapture. (#1375) ...

ps: DirectX 12 example (#302) may want to adopt that as well.

Examples: GLFW+GL2/GL3: Minor tweaks, comments.

Examples: DirectX9/10/11: Added WM_SYSKEYDOWN / WM_SYSKEYUP handlers so e.g. VK_MENU can be read.

Examples: DirectX9/10/11: Renamed WndProc handler to use a generic Win32 name + returning 0 to all messages is more correct.

Examples: DirectX10, DirectX11: Using SetCapture/ReleaseCapture to get correct behavior (#1375) ...

ps: DirectX 12 example (#302) may want to adopt that as well.

Examples: DirectX9: Using SetCapture/ReleaseCapture to get correct behavior (#1375)

Fixed compilation for #1375 + coding style fixes.