InputScalarN/DragScalarN/SliderScalarN can mess up the layout when called with only one component

[Nahor]

Version/Branch of Dear ImGui:

Version: v1.90
Branch: docking

My Issue/Question:

XxxScalarN, through PushMultiItemsWidths, pushes a minimum of two entries into ItemWidthStack, but only pops as many as there are components. If one (or less) component is used, there will be one (or more) leftover entry in the stack, which can then mess up the layout of subsequent widgets.

Screenshots/Video

Expected result:

Actual result:

Standalone, minimal, complete and verifiable example: (see #2261)

ImGui::PushItemWidth(100);

float f[2] = {0.0f, 0.0f};
float min = 0, max = 1;
ImGui::InputScalarN("foo", ImGuiDataType_Float, f, 1, &min, &max); // DO NOT WORK (1 component)
//ImGui::InputScalarN("foo", ImGuiDataType_Float, f, 2, &min, &max); // WORKS (2 components)
//ImGui::InputScalar("foo", ImGuiDataType_Float, f); // WORKS (single-scalar-only version)

ImGui::PopItemWidth();  // should pop the 100 from above, but pops the leftover entry instead

char buf[10];
ImGui::InputFloat("bar", f); // width of 100 instead of being automatically computed

[ocornut]

Thank you for the report! I have pushed a fix as 1fade35.
Given the fix itself was fairly simple I have used your name in the changelog.

[Nahor]

Still breaks if there are 0 (or negative) components. "foo" widget won't show, but "bar" is still the wrong size and will have double the vertical spacing with the last visible component.
(Probably an assert would be a good enough option for that since it doesn't make much sense as a use case but it would avoid a lot of head scratching if someone triggers it anyway)

[ocornut]

Added an assert for it.